thesis about the manhattan project

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Creation of the U.S. atomic weapons program

Manhattan project expansion under groves and oppenheimer, the first atomic bombs: trinity, hiroshima, and nagasaki, operation crossroads and the end of the manhattan project.

What led to the Manhattan Project?

Who were the most important scientists associated with the manhattan project, what did the manhattan project do, what were the immediate and long-term results of the manhattan project.

• What did J. Robert Oppenheimer do in the Manhattan Project?

Manhattan Project

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• Energy.gov - The Manhattan Project
• Atomicarchuve.com - The Manhattan Project: Making the Atomic Bomb
• National Park Service - What is the Manhattan Project?
• Spartacus Educational - Manhattan Project
• Carnegie Mellon University - Encyclopedia of the History of Science - Manhattan Project
• Live Science - What was the Manhattan Project?
• Chemistry LibreTexts - The Manhattan Project - Labs and Fuel
• Atomic Heritage Foundation - The Manhattan Project
• Manhattan Project - Student Encyclopedia (Ages 11 and up)
• Table Of Contents

In 1939, American scientists, many of whom had fled from fascist regimes in Europe, were aware of advances in nuclear fission and were concerned that Nazi Germany might develop a nuclear weapon. The physicists Leo Szilard and Eugene Wigner persuaded Albert Einstein to send a letter to U.S. President Franklin D. Roosevelt warning him of that danger and advising him to establish an American nuclear research program. The Advisory Committee on Uranium was set up in response. The beginning of the Manhattan Project can be dated to December 6, 1941, with the creation of the Office of Scientific Research and Development, headed by Vannevar Bush .

American physicist J. Robert Oppenheimer headed the Manhattan Project, with the goal of developing the atomic bomb , and Edward Teller was among the first recruited for the project. Leo Szilard and Enrico Fermi built the first nuclear reactor . Ernest Orlando Lawrence was program chief in charge of the development of the electromagnetic process of separating uranium-235 .

Other notable researchers included Otto Frisch , Niels Bohr , Felix Bloch , James Franck , Emilio Segrè , Klaus Fuchs , Hans Bethe , and John von Neumann . The person who oversaw the Manhattan Project, however, was not a scientist. He was Leslie Groves , a brigadier general in the U.S. Army.

The Manhattan Project produced the first atomic bomb . Several lines of research were pursued simultaneously . Both electromagnetic and fusion methods of separating the fissionable uranium-235 from uranium-238 were explored at Oak Ridge in Tennessee. The production of plutonium-239, first achieved at the University of Chicago , was further pursued at the Hanford Engineer Works in Washington state. In the meantime, at Los Alamos , New Mexico, scientists found a way to bring the fissionable material to supercritical mass (and thus explosion) and to control the timing and devised a weapon to house it. The first test, on July 16, 1945, at Alamogordo air force base in New Mexico, produced a massive nuclear explosion.

Although many physicists were opposed to the actual use of the atomic bomb created by the Manhattan Project, U.S. President Harry S. Truman believed that the bomb would persuade Japan to surrender without requiring an American invasion. Accordingly, on August 6, 1945, a U.S. airplane dropped an atomic bomb on Hiroshima , killing at least 70,000 people instantly (tens of thousands more died later of radiation poisoning). Three days later, another U.S. aircraft dropped a bomb on Nagasaki . Since then, a number of countries have concluded that possession of nuclear arms is the best way to guarantee their safety, despite fears that nuclear proliferation increases the chances of the use of such a weapon.

Manhattan Project , U.S. government research project (1942–45) that produced the first atomic bombs . See Britannica’s interactive timeline of the Manhattan Project.

American scientists, many of them refugees from fascist regimes in Europe, took steps in 1939 to organize a project to exploit the newly recognized fission process for military purposes. The first contact with the government was made by G.B. Pegram of Columbia University , who arranged a conference between Enrico Fermi and the Navy Department in March 1939. In the summer of 1939, Albert Einstein was persuaded by his fellow scientists to use his influence to present the military potential of an uncontrolled fission chain reaction to Pres. Franklin D. Roosevelt . In February 1940, $6,000 was made available to start research under the supervision of a committee headed by L.J. Briggs, director of the National Bureau of Standards (later National Institute of Standards and Technology ). On December 6, 1941, the project was put under the direction of the Office of Scientific Research and Development, headed by Vannevar Bush .

After the U.S. entered World War II , the War Department was given joint responsibility for the project, because by mid-1942 it was obvious that a vast array of pilot plants, laboratories, and manufacturing facilities would have to be constructed by the U.S. Army Corps of Engineers for the assembled scientists to carry out their mission. In June 1942 the Corps of Engineers’ Manhattan District was initially assigned management of the construction work (because much of the early research had been performed at Columbia University, in Manhattan ), and in September 1942 Brig. Gen. Leslie R. Groves was placed in charge of all Army activities (chiefly engineering activities) relating to the project. “Manhattan Project” became the code name for research work that would extend across the country.

It was known in 1940 that German scientists were working on a similar project and that the British were also exploring the problem. In the fall of 1941 Manhattan Project chemist Harold C. Urey accompanied Pegram to England to attempt to set up a cooperative effort, and by 1943 a combined policy committee was established with Great Britain and Canada . In that year a number of British and Canadian scientists moved to the United States to join the project.

If the project were to achieve timely success, several lines of research and development had to be carried on simultaneously before it was certain whether any might succeed. The explosive materials then had to be produced and be made suitable for use in an actual weapon.

Uranium-235 , the essential fissionable component of the postulated bomb, cannot be separated from its natural companion, the much more abundant uranium-238 , by chemical means; the atoms of these respective isotopes must rather be separated from each other by physical means. Several physical methods to do this were intensively explored, and two were chosen—the electromagnetic process developed at the University of California , Berkeley , under Ernest Orlando Lawrence and the diffusion process developed under Urey at Columbia University. Both of these processes, particularly the diffusion method, required large, complex facilities and huge amounts of electric power to produce even small amounts of separated uranium-235. Philip Hauge Abelson developed a third method called thermal diffusion, which was also used for a time to effect a preliminary separation. These methods were put into production at a 70-square-mile (180-square-km) tract near Knoxville , Tennessee , originally known as the Clinton Engineer Works, later as Oak Ridge .

Only one method was available for the production of the fissionable material plutonium-239 . It was developed at the metallurgical laboratory of the University of Chicago under the direction of Arthur Holly Compton and involved the transmutation in a reactor pile of uranium-238. In December 1942 Fermi finally succeeded in producing and controlling a fission chain reaction in this reactor pile at Chicago.

Quantity production of plutonium-239 required the construction of a reactor of great size and power that would release about 25,000 kilowatt-hours of heat for each gram of plutonium produced. This required the development of chemical extraction procedures that would work under conditions never before encountered . An intermediate step in putting this method into production was taken with the construction of a medium-size reactor at Oak Ridge. The large-scale production reactors were built on an isolated 1,000-square-mile (2,600-square-km) tract on the Columbia River north of Pasco , Washington—the Hanford Engineer Works .

Before 1943, work on the design and functioning of the bomb itself was largely theoretical, based on fundamental experiments carried out at a number of different locations. In that year a laboratory directed by J. Robert Oppenheimer was created on an isolated mesa at Los Alamos , New Mexico , 34 miles (55 km) north of Santa Fe . This laboratory was tasked with developing methods to reduce the fissionable products of the production plants to pure metal and fabricate the metal to required shapes. Methods of rapidly bringing together amounts of fissionable material to achieve a supercritical mass (and thus a nuclear explosion) had to be devised , along with the actual construction of a deliverable weapon that would be dropped from a plane and fused to detonate at the proper moment in the air above the target. Most of these problems had to be solved before any appreciable amount of fissionable material could be produced, so that the first adequate amounts could be used at the fighting front with minimum delay.

By the summer of 1945, amounts of plutonium-239 sufficient to produce a nuclear explosion had become available from the Hanford Works, and weapon development and design were sufficiently advanced so that an actual field test of a nuclear explosive could be scheduled. Such a test was no simple affair. Elaborate and complex equipment had to be assembled to provide a complete diagnosis of success or failure. By this time the original $6,000 authorized for the Manhattan Project had grown to $2 billion.

The first atomic bomb was exploded at 5:30 am on July 16, 1945, at the Alamogordo air base 120 miles (193 km) south of Albuquerque , New Mexico. Oppenheimer had called the site “Trinity” in reference to one of John Donne ’s Holy Sonnets . The bomb—a plutonium implosion device called Gadget —was raised to the top of a 100-foot (30-meer) steel tower that was designated “Zero.” The area at the base of the tower was marked as “Ground Zero,” a term that would pass into common parlance to describe the center of an (often catastrophic) event. The tower was surrounded by scientific equipment, with remote monitoring taking place in bunkers occupied by scientists and a few dignitaries 10,000 yards (9 km) away. The explosion came as an intense light flash, a sudden wave of heat, and later a tremendous roar as the shock wave passed and echoed in the valley. A ball of fire rose rapidly, followed by a mushroom cloud extending to 40,000 feet (12,200 meters). The bomb generated an explosive power equivalent to 15,000 to 20,000 tons of trinitrotoluene (TNT); the tower was completely vaporized and the surrounding desert surface fused to glass for a radius of 800 yards (730 meters).

The following month, two other atomic bombs produced by the project, the first using uranium-235 and the second using plutonium, were dropped on the Japanese cities of Hiroshima and Nagasaki. Neither city had been attacked during the U.S. strategic bombing campaign until that point, and planners wished to demonstrate the destructive power of the bombs. Hiroshima was selected as the primary target because of its military value; the city served as the headquarters of the Japanese Second Army. On August 6, 1945, at about 8:15 am local time, a U.S. B-29 bomber released a gun assembly fission bomb—dubbed Little Boy —above Hiroshima. The weapon detonated at an altitude of 1,900 feet (580 meters), and the explosive yield was estimated to be the equivalent of 15,000 tons of TNT. Some 70,000 people were killed instantly, and by the end of the year the death toll had surpassed 100,000. Two-thirds of the city area was destroyed.

By the morning of August 9, 1945, the Soviet Union had declared war on Japan, but the Japanese government had not yet communicated its intent to surrender to the Allies . A B-29 carrying Fat Man —a plutonium implosion bomb similar to the one used in the Trinity test—was initially dispatched to Kokura (now part of Kitakyūshū , Japan). Thick clouds and haze over Kokura prevented the bombardier from sighting the designated aimpoint, however, and the bomber proceeded to its secondary target, the port city of Nagasaki . At 11:02 am Fat Man exploded at an altitude of 1,650 feet (500 meters) northwest of the city center. The bomb detonated with the explosive force of 21,000 tons of TNT. An estimated 40,000 people were killed instantly, and at least 30,000 more would die from their injuries and radiation poisoning by the end of the year. About 40 percent of the city’s buildings were completely destroyed or severely damaged. Due to the area’s uneven terrain, a significant part of Nagasaki—particularly in the southeastern industrial and government district—was relatively unscathed . The Japanese initiated surrender negotiations the next day. By this point, Groves had notified U.S. Pres. Harry S. Truman that another bomb would be ready for delivery within a week.

On September 2, 1945, a Japanese delegation signed formal surrender documents on the deck of the USS Missouri . Shortly after the conclusion of hostilities, Manhattan Project physicist Philip Morrison traveled to Hiroshima at the request of the War Department to study the effects of the atomic bomb. Characterizing the bomb as “preeminently a weapon of saturation,” he said, “It destroys so quickly and so completely such a large area that defense is hopeless.” Horrified by what he had witnessed , Morrison would spend the rest of his life campaigning against nuclear weapons and a potential “third bomb.”

After the war, the Manhattan Project oversaw Operation Crossroads, a military-scientific experiment conducted at Bikini atoll in the South Pacific in 1946. “Able,” the first peacetime atomic weapons test, was carried out on July 1, 1946. In attendance were some 42,000 U.S. military personnel, as well as more than 100 journalists and representatives from a dozen foreign countries. A 20-kiloton atomic bomb was dropped from a B-29 and exploded at an altitude of about 520 feet (158 meters) over a fleet of about 80 decommissioned World War II naval vessels. Only five ships were sunk by the blast, and, although several more were damaged, the majority survived the explosion relatively unscathed. Within a day, radiation levels had subsided enough for the ships to be boarded and inspected. Press and foreign military observers seemed underwhelmed that the blast had not vaporized the assembled ships, but such an appraisal discounted the debilitating effect that radiation would have had on a ship’s crew. Many test animals placed throughout the fleet quickly succumbed to radiation sickness , confirming a prediction in the Bulletin of the Atomic Scientists that “a large ship, about a mile away from the explosion, would escape sinking, but the crew would be killed by the deadly burst of radiations from the bomb, and only a ghost ship would remain, floating unattended on the vast waters of the ocean.”

The second test, “Baker,” took place on July 25, 1946. A 23-kiloton device was suspended at a depth of 90 feet (27 meters) from a decommissioned landing craft in the Bikini lagoon. At the moment of the explosion, a luminous dome rose on the surface of the lagoon, followed by an opaque cloud that enveloped about half the target area. The cloud dissipated within seconds, revealing a column of ascending water that lifted the 26,000-ton battleship USS Arkansas into the air for a brief moment. The column of water, some 2,200 feet (670 meters) in diameter, rose to a height of 1 mile (1.6 km), sending spray still higher. The expanding column of spray engulfed about half the ships in the target fleet with radioactive water. Waves traveling outward from the explosion were up to 100 feet (30 meters) tall, even at a distance of 1,000 feet (some 300 meters) from the epicenter . The evaluation board of the Joint Chiefs of Staff reported that the explosion had produced intense radioactivity in the waters of the lagoon. The target ships were saturated with radioactive water so lethal that four days after the test, it was still unsafe for inspection parties to spend “any useful length of time” in the center of the target area or on any of the ships anchored there. Persistent radiation and the difficulty of decontamination led to the cancellation of “Charlie,” a planned third test that would have involved a bomb being detonated at the bottom of the Bikini lagoon.

After the conclusion of Operation Crossroads, the Manhattan District relinquished direction of the plants and laboratories under its jurisdiction to the U.S. Atomic Energy Commission (AEC), a civilian agency established by act of Congress in August 1946. Under the AEC, weapon development and testing continued along with development of the peaceful uses of atomic energy . The U.S. government disbanded the AEC under the Energy Reorganization Act of 1974 and divided its functions between two new agencies: the Nuclear Regulatory Commission , which regulates the nuclear power industry, and the Energy Research and Development Administration, which was eliminated in 1977 when the Department of Energy was created.

Encyclopedia of the History of Science

Manhattan project.

• Alex Wellerstein – Stevens Institute of Technology

The Manhattan Project was the Anglo-American effort to build nuclear weapons during World War II. It is commonly regarded as one of the most successful, if controversial, mega-projects of the 20th century, bringing together scientific expertise, industrial production, and military coordination to create an entirely new industry, and new form of weaponry, in an unusually compressed timescale. Within the literature of the history of science and technology, the Manhattan Project has been examined from a number of different vantage points, often centering on the role of the thousands of academic scientists in hundreds of centers who participated in the weaponization of a new scientific discovery to facilitate the mass slaughter of civilians, but also portraying the project as a prototype of future military-industrial-academic collaborations.

Historiographical background

The Manhattan Project per se specifically refers to the overarching weapons-production program begun in late 1942, and not to earlier research and pilot programs. It is related to but not exactly the same as the Manhattan Engineer District, the division of the US Army Corps of Engineers that was in charge of implementing the development of the atomic bomb, and which maintained control over the technology until January 1947, when the civilian US Atomic Energy Commission took over all production operations.

This definitional issue is not an insubstantial one. If one assigns the moniker of the Manhattan Project to the earliest investigations into nuclear fission, it results in a significantly different narrative about the purpose and origins of the weapons project, and obscures the distinct change of direction that took place in late 1942. At times, it was in the interest of government officials involved in making the atomic bomb to stress the continuity with earlier research, as the original motivation for the project (fear of the Nazis) was seen as easier to justify than the later stages of it. 1

The background story of events leading to the Manhattan Project has been told in several different modes. The most common is as the history of physics: the discovery of X-rays in 1895 led directly to new theories and models of the world that, in turn, posed questions about the fundamental nature of atomic structure. These in turn led to the discovery of nuclear fission, through which subatomic neutrons can be made to split heavy atomic nuclei (like uranium) and release extremely large amounts of energy. The discovery of the nuclear chain reaction suggested that this energy release could be exponentially amplified by human intervention. This mode of background story is favored in popular accounts and was also the one preferred by the scientists who crafted the first version of this history, in part because it reflected their institutional interests (the promotion of basic scientific research), but also because it fit in with their historical self-identification as physicists. 2

There have been other ways to frame this story. Historians of technology in particular have tended to look at the continuities with other industrial-governmental operations in the United States, such as the Tennessee Valley Authority, and some historians of science have also emphasized the important bureaucratic aspects necessary as a prerequisite for undertaking such an extremely risky project. And several historians of science have also emphasized that the “first” nuclear age, ranging from the discovery of radioactivity and ending with the discovery of fission, was responsible for many of the scientific and cultural frameworks that were later applied to the problem of atomic weapons. 3

An endeavor as large as the Manhattan Project can contain multitudes of historical frameworks simultaneously. It is difficult to overemphasize the scale of the work. Its wartime cost ($2 billion 1945 USD, around $30-50 billion USD today, depending on the conversion factors used) was more impressive at the time than it is in the context of later American military expenditures (for comparison, the most expensive wartime project by the United States was the research and production of the B-29 Superfortress, which cost about $3 billion 1945 USD). Its cost alone does not do justice to its scale, however. At its peak, it employed over 125,000 direct staff members, and probably a larger number of additional people were involved through the subcontracted labor that fed raw resources into the project. Because of the high rate of labor turnover on the project, some 500,000 Americans worked on some aspect of the sprawling Manhattan Project, almost 1% of the entire US civilian labor force during World War II. In 1943, the project was estimated to be consuming approximately over half of all Army construction labor and steel production, and the Oak Ridge site alone used approximately 1% of the electrical power produced for the entire country. The Manhattan Project was responsible for the generation of thousands of new inventions, as represented by patent claims processed in secret by the project, which if filed would have represented some 1% of all patents in force at the end of World War II. And while much attention has been given to the “big three” project production sites (Hanford, Los Alamos, and Oak Ridge), the total project sites across the United States number into the hundreds, including work done at over two dozen universities. It was not merely a scientific research project: it entailed the creation of an entirely new industry as well as the military coordination required to mobilize its byproducts as usable weapons, all under an unusually heavy cloak of military and governmental secrecy. 4

All of this, it should be emphasized, was done on a project that literally emerged in part out of a genre of science fiction and carried a significant risk of failure. 5 As it was, the project just managed to produce three atomic bombs by the summer of 1945; had it been delayed a few months more, it very easily could not have produced nuclear weapons prior to an American invasion of Japan, or the end of the war by some other means. This possibility of failure was acutely felt by those who worked on the project at the time, though knowledge of its outcome has led many narratives about its history to carry an air of inevitability. 6 Most exceptional about the Manhattan Project was its haste: all of its major activity took place within the span of three years (1942-1945), which is still the world-record for any nuclear weapons production program.

The decision to make the atomic bomb

The Manhattan Project, and the atomic bomb itself, could not have been imagined as plausible prior to the discovery of nuclear fission by Otto Hahn, Fritz Strassman, Lise Meitner, and Otto Frisch in the winter of 1938. Nuclear fission — the splitting of heavy nuclei (originally uranium) through the bombardment of neutrons — and the subsequent (early 1939) concept of the nuclear chain reaction provided the first concrete mechanism towards controlling the rate of nuclear reactions and inducing them towards exponential reactions that might cause explosions. For the context of the Manhattan Project, it suffices to note that by the early 1940, scientists in several nations (France, Germany, the United Kingdom, and the United States, with Japan following in 1941 and the Soviet Union in 1942) had petitioned their governments to support further research into the possible military applications of the fissioning of uranium. 7

The early programs of Germany, the United Kingdom, and the United States are of brief note in relation to the later Manhattan Project. In Germany, a Uranverein (“Uranium Club”) was created under the auspices of the Reich Research Council with the blessing of Army Ordnance, and had the goal of exploring whether nuclear reactions could have military application, notably through the use of nuclear reactors. Similar work was undertaken by the Uranium Committee in the United States, created within the National Bureau of Standards in late 1939 by US President Franklin D. Roosevelt as a result of the urging of a letter signed by Albert Einstein (drafted at the impetus and with the input of Leo Szilard, the Hungarian refugee physicist who had first conceived of the nuclear chain reaction). In the United Kingdom, similarly, a small group of scientists sparked by the concerns of continental refugees, later known as the MAUD Committee, commenced with research at a small scale. 8

None of these efforts started in 1939 constituted a nuclear weapons production program. Their goals were, in essence, to answer the question of feasibility regarding the military application of nuclear fission, whether in terms of nuclear reactors (machines that produced controlled nuclear fission reactions) or weapons (machines that produced explosive reactions). Their work was, by the later standards of the Manhattan Project, extremely small scale. To put it into perspective, the entire budget expended by the US government on nuclear fission research between 1939 and 1941 was around $15 million USD. For the year of 1944, by contrast, the Army spent on average $2.5 million USD per day on the effort. 9

This early work proceeded at a pace not exceptionally different from “normal” scientific research. Innumerable uncertainties, unknowns, and questions existed; it was not at all clear that the technology was weaponizable in the short term. In Germany, in early 1942, the work was reviewed by Army Ordnance with the question of whether it was worth committing to a major effort — whether it would play a favorable role in the war’s outcome. The decision was negative. Though the idea of a nuclear weapon was judged technically feasible, the expense, risks, and time-scale involved, coupled with the German belief that the war would conclude in the near-term in their favor, motivated them to pursue only a relatively small nuclear reactor development program and not an expansive weapons program. (If the nuclear reactor program had been successful in producing a working reactor, it is possible that might have changed their position on the feasibility of nuclear weapons, though even then it is hard to imagine, with the knowledge of the state of Germany in the later portion of the war, that the program would have been successful in producing a weapon in time to be useful.) Though the German program has often been judged negatively (e.g., as “failure” in the “race” for the atomic bomb), considerable careful scholarship has demonstrated that the German understanding of the feasibility of nuclear weapons in 1942 was not a matter of ignorance so much as it was a decision of resource-allocation and risk-assessment. 10

The effort of the United States, left to its own devices, very well could have gone the same way. The early program was not exceptionally well-managed (it was, some participants later argued, plagued by too much secrecy at too early a period of time), and the top American scientist-administrators who controlled the direction of American wartime research and development, such as Vannevar Bush and James B. Conant, were skeptical that the effort was worth a great expenditure of resources and scientific manpower. Again, the problem here was not so much a lack of understanding, but perhaps too much understanding: it was felt that the technical difficulties of producing fuel for the weapon (enriched uranium) were extraordinarily high and that the coming war’s requirements for scientific manpower were going to be large even without such a program. 11

The British program, by contrast, came to very different conclusions. Otto Frisch and Rudolf Peierls, two refugee scientists from Europe who especially feared the prospect of Nazis armed with nuclear weapons, concluded through theoretical calculation that the enriched-uranium fuel requirements for a bomb would be considerably smaller than had been believed (they were in retrospect overly optimistic; ironically, the Germans actually made more accurate predictions about this), and that while the effort would be a significantly risky undertaking for the wartime United Kingdom, it would be a feasible undertaking for either the United States or Germany. These conclusions were codified by the MAUD Committee, with the recommendations that they be sent to American scientific authorities, meant both to warn them of the German possibility and encourage them to broader action. This occurred in the spring of 1941, though the report was not given broad circulation. In the summer of 1941, the British sent a scientific emissary to the United States to investigate the lack of action, and this emissary (Mark Oliphant) succeeded in getting the attention and interest of several key American scientists (the aforementioned Bush, along with Ernest Lawrence, Arthur Compton, and Harold Urey). 12

The American program was soon completely re-organized and renamed. Gone was the revealing moniker of the Uranium Committee, and in its place the work was renamed the S-1 Committee, the blandness of the name a sure sign of its newfound perceived importance. This work was not yet a weapon production program: the goal of the S-1 work was to produce proof-of-concept facilities that would demonstrate the means by which uranium could be enriched and a new element, plutonium, could be produced from nuclear reactors. 13

The S-1 work began in the fall of 1941, under the auspices of the Office for Scientific Research and Development, the civilian agency created by Roosevelt at the behest of Vannevar Bush (who would oversee it), to coordinate scientific research and development for defense purposes. By the summer of 1942, Bush was confident enough in the enterprise to recommend to Roosevelt that an all-out “crash” effort to develop an atomic bomb should be put into place, with the majority of the organization taken over by the US Army Corps of Engineers. The initial work had its offices in New York City, near to the headquarters of major industrial contractors and the scientific work being done at Columbia University, and the new organization was thus named the Manhattan Engineer District. The recommendation was based on technical promise, but also on the strong and, at the time authentic, belief that the Germans could be even farther ahead at that point and that they were in a genuine “race” for the bomb. 14

In several reports in the summer and winter of 1942, Bush and Conant recommended Roosevelt increase the effort involved in fission research. Though their optimism was somewhat tempered by the end of the year (in June, they believed weapons would be ready by 1944; in December, they believed that they would have six bombs by the first half of 1945), they recommended an all-out effort that would cost $400 million USD, to be dispensed through secret channels. These funds would be used to construct several plants for the enrichment of uranium, as well as the construction of at least one industrial-sized nuclear reactor and the facilities necessary to create plutonium. Roosevelt approved their initiatives without reservation, and the Army Corps of Engineers was brought in to coordinate the work of constructing the requisite plants; at this point, the American effort was indeed a weapons-production program, with the aim of producing usable weapons within the span of the war, though the specifics of their use had not yet been discussed. 15

To reiterate: The American decision to develop nuclear weapons was hardly straightforward. Despite American scientists’ conclusion that producing nuclear weapons would be extremely difficult, key figures in the conduct of wartime science were convinced by the United Kingdom’s advocacy that it was a risk worth taking. The peculiar structure of American wartime scientific planning also meant that the question was given considerably little oversight — all information on the issue was funneled from Bush to Roosevelt, who himself approved the creation of a sweeping program without apparent consultation with any outside bodies or advisors. Had the overall program been somewhat more bureaucratically controlled, with further stakeholders involved in the decision-making process, it is very easy to imagine that at the very least any initiative would have been delayed or avoided altogether. The development of nuclear weapons during World War II is, in many ways, an unexpected and improbable outcome, and instead of asking why other nations did not develop such weapons, it is more fruitful to look instead at the various contingent and at times even coincidental factors that led to the United States being the only nation to pursue such a program with vigor.

The work of the Manhattan Project

In the initial stages of the American fission effort (1939-1942), scientists at a variety of university laboratories — notably Columbia University, the University of Chicago, and the University of California–Berkeley, among many others— identified key processes for the development of the “fissile material” fuel that is necessary for a nuclear weapon to operate.

The first approach considered was the isotopic enrichment of uranium. (Chemical elements can vary in the number of neutrons in their nucleus, and these different forms are known as isotopes.) It was discovered as early as 1939 that only one isotope of uranium was fissionable by neutrons of all energies, and by 1941 it was understood that to make a fission weapon required a reasonably pure amount of material that met this criterion. Less than 1% of the uranium as mined is the fissile uranium-235 isotope, with the other 99% being uranium-238, which inhibits nuclear chain reactions. It was understood by 1941 that to make a weapon the fissile uranium-235 would need to be separated from the non-fissile uranium-238, and that because they were chemically identical this could only be accomplished through physical means that relied on the small (three neutron) mass difference between the atoms. Isotopic separation had been undertaken for other elements (for example, the separation of the hydrogen isotope deuterium from the bulk of natural water), but never on a scale of the sort contemplated for the separation of uranium. 16

Several methods were proposed and explored at small scales at various research sites in the United States. The preferred candidates by the end of the first year of the Manhattan Project (1942) were:

Electromagnetic separation, in which powerful magnetic fields were used to create looping streams of uranium ions that would slightly concentrate the lighter isotope at the fringes. This work was related to the cyclotron concept pioneered by Ernest Lawrence at the University of California, and the bulk of the research took place at his Radiation Laboratory.

Gaseous diffusion, in which a gaseous form of uranium was forced through a porous barrier consisting of extremely fine passageways. The gas molecules containing the lighter isotope would navigate the barrier slightly faster than the gas molecules containing the heavier isotope, although the effect would have to be magnified through many stages before it resulted in significant separation. This work was originally explored primarily at Columbia University under the guidance of Harold Urey and others.

Thermal diffusion, in which extreme heat and cold were applied to opposite sides of a long column of uranium gas, which also resulted in slight separation, with the lighter uranium isotope concentrating at one end. This was initially investigated by Philip Abelson at the Naval Research Laboratory.

Centrifugal enrichment, in which the rapid spinning of a uranium gas allowed for the slight concentration of the lighter element at the center of the whirling mixture, a process that would also require a large number of “stages” to be successful. This was pursued by physicist Jesse W. Beams at the University of Virginia and at the Standard Oil Development Company in New Jersey. 17

Over the course of 1943, centrifugal enrichment proved less promising than the other methods, and by 1944 the method was essentially abandoned (though it would, in the postwar period, be perfected by German and Austrian scientists working in the Soviet Union). Because it was unclear which of the other techniques would be most successful at scale, both the electromagnetic and gaseous diffusion methods were pursued with great gusto, and arguably constituted the most substantial portion of the Manhattan Project. The construction and operation of the two massive facilities required for these methods (the Y-12 facility for the electromagnetic method, and K-25 facility for the gaseous diffusion method) alone made up 52% of the cost of the overall project, and all of the Oak Ridge facilities together totaled 63% of the entire project cost. While thermal diffusion was initially imagined as a competitor process, difficulties in achieving the desired level of enrichment led to all three methods being “chained” together as a sequence: the raw uranium would be enriched from the natural level of 0.72% uranium-235 to 0.86% at the thermal diffusion plant, and its output would then be enriched to 23% at the gaseous diffusion plant, and then finally enriched to an average level of 84% at the electromagnetic plants. 18

The plants for the production of enriched uranium were constructed in Oak Ridge, Tennessee, an isolated site that was chosen primarily for its proximity to the large electrical resources provided by the Tennessee Valley Authority. The Oak Ridge site (Site X) employed over 45,000 people for construction at its peak, and had a similar number of employees on the payroll for managing its continued operations once built. A “secret city,” the facility relied on heavy compartmentalization (“need to know”) so that practically none of its thousands of employees had any real knowledge of what they were producing. Every aspect of life in Oak Ridge was controlled by contractors and the military, in the aim of producing weapons-grade material in maximum haste and with a minimum of security breaches. Situated in the Jim Crow South, the facility was entirely segregated by law, and living conditions between African-Americans and whites varied dramatically. Various industrial contractors managed the different plants (for example, the Union Carbide and Carbon Corporation operated K-25, and the Tennessee Eastman Corporation operated Y-12). 19

In the process of researching the possibility of nuclear fission, another road to a bomb had made itself clear. Nuclear reactors had been contemplated as early as nuclear weapons. Where a nuclear weapon requires high concentrations of fissile material to function, a reactor does not: a controlled nuclear reaction (as opposed to an explosive one) can be developed through natural or slightly-enriched uranium through the use of a substance called a “moderator,” which slows the neutrons released from fission reactions. Under the right conditions, this allows a chain reaction to proceed even in unenriched material, and the reaction is considerably slower, and much more controllable, than the kind of reaction that occurs inside of a bomb.

Nuclear reactors had been explored as possible energy sources, though engineering difficulties would make this use of them more difficult than was anticipated (the first nuclear reactors for power purposes in the United States did not go critical until 1958). More importantly for the wartime planners, it was realized that the plentiful uranium-238 isotope, while not fissile, could still be quite useful. When uranium-238 absorbs a neutron, it does not undergo fission, but instead transmutes into uranium-239. Uranium-239, however, is unstable, and through a series of nuclear decays becomes, in the span of a few days, the artificial element plutonium-239. Isolated for the first time in February 1941, plutonium was calculated and confirmed to have very favorable nuclear properties (it is even more reactive than uranium-235, and thus even less of it is necessary for a chain reaction). 20

The first controlled nuclear reaction was achieved in December 1942 at the University of Chicago, by a team led by Enrico Fermi. The first reactor, Chicago Pile-1, used purified graphite as its moderator and 47 tons of natural (unenriched) uranium in the form of metal ingots. Even while the pilot Chicago Pile-1 reactor was still being constructed, plans were being made for the creation of considerably larger, industrial-sized nuclear reactors at a remote site in Hanford, Washington, constructed and operated by E.I. du Pont Nemours & Co. (DuPont). The Hanford site (Site W) was chosen largely for its proximity to the Columbia River, whose water would be used for cooling purposes. On dusty land near the river, three large graphite-moderated reactors were constructed starting in 1943, with the first reactor going critical in September 1944. A massive chemical facility known as a “canyon” was constructed nearby, by which, largely through automation and remote control, the irradiated fuel of the reactors was chemically stripped of its plutonium. This process involved dangerously radioactive materials, chemically noxious substances (powerful acids), and was fairly inefficient (every ton of uranium fuel that was processed yielded 225 grams of plutonium). 21

The labor conditions at Hanford varied considerably from Oak Ridge. Where Oak Ridge was imagined as a cohesive community, Hanford was not, and employed an abundance of cheap labor in far inferior work conditions (and those at Oak Ridge were not so great to begin with). The radioactive and chemical wastes at the site were treated in an expedient, temporary fashion, with the idea that in the less-hurried future they would be more properly eliminated. Subsequent administrations continued this approach for decades. Hanford became regarded as the most radioactively contaminated site in the United States, and since the end of the Cold War has been involved in expensive cleanup and remediation efforts. The Hanford project constituted about 21% of the total cost of the Manhattan Project. 22

The work of these two sites — Oak Ridge and Hanford — constituted the vast bulk of the labor and expense of the Manhattan Project (roughly 80% of both). Without fuel, there could be no atomic bomb: it was and remains a key chokepoint in the development of nuclear weapons. As a result, it is important to conceptualize the Manhattan Project as much more than just basic science alone: without an all-out military-industrial effort, the United States would not have had an atomic bomb by the end of World War II.

The head of the Manhattan Project’s entire operation was Brigadier General Leslie R. Groves, a West-Point trained engineer who had previously been instrumental in the construction of the Pentagon building. Groves had accepted the assignment reluctantly, liking neither the risk of failure nor the fact that it was a home-front assignment. But once he accepted the job, he was determined to see it through to success. His unrelenting drive resulted in the Manhattan Project being given the top level of priority of all wartime projects in the United States, which allowed him nearly unfettered access to the resources and labor necessary to build a new atomic empire. Groves amplified the degree of secrecy surrounding the project through his application of compartmentalization (which he considered “the very heart of security”), and his own autonomous domestic and even foreign intelligence and counter-intelligence operations, making the Manhattan Project a virtual government agency of its own. (Despite these precautions, the project was, it later was discovered, compromised to the Soviet Union by several well-placed spies.) While it is uncharacteristic to associate the success or failure of massive projects with single individuals, it has been plausibly argued that Groves was perhaps the most “indispensable” individual to the project’s success, and that his willingness to accelerate and amplify the work being done in the face of setbacks, and to bully his way through military and civilian resistance, was essential to the project achieving its results when it did. 23

Though the scientific research on the project was initially dispersed among several American universities, as the work moved further into the production phase civilian and military advisors to the project concurred that the most sensitive research work, specifically that on the design of the bomb itself, should be located somewhere more secure than a university campus in a major city. Bush, Conant, and Arthur Compton had all come to the conclusion that a separate, isolated laboratory should be created for this final phase of the work. In late 1942, Groves identified Berkeley theoretical physicist J. Robert Oppenheimer as his preferred candidate for leading the as-yet-created laboratory, and on Oppenheimer’s recommendation identified a remote boys’ school in Los Alamos, New Mexico, as the location for the work. Initially imagined to be fairly small, the Los Alamos laboratory (Site Y) soon became a sprawling operation that took on a wide variety of research projects in the service of developing the atomic bomb, ending the war with over 2,500 people working at the site. 24

Though the work of the bomb was even at the time most associated with physicists, it is worth noting that at Los Alamos, there were roughly equal numbers of physicists, chemists, metallurgists, and engineers. The physics-centric narrative, promulgated in part by the physicists themselves after the war (in part because the physics of the atomic bomb was easier to declassify than other aspects), obscures the multidisciplinary research work that was required to turn table-top laboratory science into a working weapon. 25

It is not exceptionally hyperbolic to say that the Los Alamos laboratory brought together the greatest concentration of scientific luminaries working on a single project that the world had ever seen. It was also highly international in its composition, with a significant number of the top-tier scientists having been refugees from war-torn Europe. This included a significant British delegation of scientists, part of an Anglo-American alliance negotiated by Winston Churchill and Roosevelt. For the scientists who went to the laboratory, especially the junior scientists who were able to work and mingle with their heroes, the endeavor took on the air of a focused and intensive scientific summer camp, and the numerous memoirs about the period at times underemphasize that the goal was to produce weapons of mass destruction for military purposes. 26

Los Alamos grew because the difficulty and scope of the work grew. Notably a key setback motivated a massive reorganization of the laboratory in the summer of 1944, when it was found that plutonium produced by nuclear reactors (as opposed to the small samples of plutonium that had been produced in particle accelerators) could not be easily used in a weapon. The original plan for an atomic bomb design was relatively simple: two pieces of fissile material would be brought together rapidly as a “critical mass” (the amount of material necessary to sustain an uncontrolled chain reaction) by simply shooting one piece into the other through a gun barrel using conventional explosives. This “gun-type” design still involved significant engineering considerations, but compared to the rest of the difficulties of the project it was considered relatively straightforward. 27

The first reactor-bred samples of plutonium, however, led to the realization that the new element could not be used in such a configuration. The presence of a contaminating isotope (plutonium-240) increased the background neutron rate of reactor-bred plutonium to levels that would pre-detonate the weapon were two pieces of material to be shot together, leading to a significantly reduced explosion (designated a “fizzle”). Only a much faster method of achieving a critical mass could be used. A promising, though ambitious, method had been previously proposed, known as “implosion.” This required the creation of specialized “lenses” of high explosives, arranged as a sphere around a subcritical ball of plutonium, that upon simultaneous detonation would symmetrically squeeze the fuel to over twice its original density. If executed correctly, this increase in density would mean that the plutonium in question would have achieved a critical mass and also explode. But the degree of simultaneity necessary to compress a bare sphere of metal symmetrically is incredibly high, a form of explosives engineering that had scarcely any precedent. Oppenheimer reorganized Los Alamos around the implosion problem, in a desperate attempt to render the plutonium method a worthwhile investment. Modeling the compressive forces, much less achieving them (and the levels of electrical simultaneity necessary) required yet another massive multidisciplinary effort. 28

As of summer 1944, there were two designs considered feasible: the “gun-type” bomb which relied upon enriched uranium from Oak Ridge, and the “implosion” bomb which relied upon separated plutonium from Hanford. The manufacture of the factories that produced this fuel required raw materials, equipment, and logistics from many dozens of sites, and together with the facilities that were involved with producing the other components of the bomb, there were several hundred discrete locations involved in the Manhattan Project itself, differing dramatically in size, location, and character. To choose a few interesting examples: a former playhouse in Dayton, Ohio, was converted into the site for the production of the highly-radioactive and highly-toxic substance polonium, which was to be used as a neutron source in the bombs, without any knowledge of the residents who lived around it; most of the uranium for the project was procured from the Congo; and a major reactor research site was created in Quebec, Canada, as part of the British contribution to the work. 29

The uncertainties involved in the implosion design meant that the scientists were not confident that it would work and, if it did work, how efficient, and thus explosive, it would be. A full-scale test of the implosion design was decided upon, at a remote site at the White Sands Proving Ground, 60 miles from Alamogordo, New Mexico. On July 16, 1945, the test, dubbed “Trinity” by Oppenheimer, was even more successful than expected, exploding with the violence of 20,000 tons of TNT equivalent (20 kilotons, in the new standard of explosive power developed by the project participants). 30 (They had considerably more confidence in the gun-type bomb, and in any case, lacked enough enriched uranium to contemplate a test of it.)

Along with the work of the creation of the key materials for the bombs and the weapons designs themselves, additional thought was put into the question of “delivery,” the effort that would be required to detonate the bomb over a target. This aspect of the project, more a concern of engineering than science per se, was itself nontrivial: the atomic bombs were exceptionally heavy by the standards of the time, and the implosion bomb in particular had an ungainly egg-like shape. The “Silverplate” program created modified versions of the B-29 Superfortress long-range heavy bombers (most of their armaments and all of their armor were removed so that they could fly higher and faster with the heavy bombs), while Project Alberta, headquartered at Wendover Army Air Field in Utah, developed the ballistic cases of the weapons while training crews in the practice of delivering such weapons with relative accuracy. 31

The use of the bombs and the legacy of the project

All of the above has been told with a minimum of attention to the ultimate questions of the Manhattan Project: whether and how to use the bombs. Indeed, from late 1944 through mid-1945, as the notion of the atomic bomb moved from the possible to the real, a large amount of policy and military planning began to go into effect. Notably, this project that had been ostensibly created to counter the threat of a German atomic bomb shifted almost imperceptibly into one dedicated to the first use of such a weapon onto Japan. By the time that serious planning for use of the weapon was beginning, in late 1944, Manhattan Project officials were more or less convinced that Germany was no longer a possible target, and posed no atomic threat.

Two committees were particularly important. The first was the Interim Committee, created by the Secretary of War, Henry Stimson, at the request of Bush and Conant in late 1944. This committee was ostensibly concerned with matters affecting the “interim” period that would exist between the use of the bombs as a weapon (or some other revelation of their existence to the world) and the creation of permanent peacetime authorities (both domestic and international) for the future control of nuclear weapons. This “interim” remit however proved extremely expansive, covering everything from the consideration of the use of the bombs in war (because that would presumably affect what came afterwards) to the preparation of press releases and plans for both domestic legislation and for the introduction of proposals to the nascent United Nations for the international regulation of nuclear technology. A Scientific Panel composed of Oppenheimer, Compton, Fermi, and Lawrence were consulted on several topics, including the postwar priorities for new nuclear research, as well as the question (sparked by a committee of scientists at the University of Chicago headed by physicist James Franck) of whether the United States would be better served by first demonstrating their new weapon in a non-violent way to Japan, rather than by using it militarily (the Scientific Panel ruled against the demonstration idea). 32

The second committee, the Target Committee, consisted of military and scientific representatives who met three times in the spring of 1945 to make the final recommendations as to exactly how the weapons ought to be used. While the initial idea of the atomic bomb was flexible enough to imagine a variety of uses (for example, against a naval base such as Japan’s Harbor of Truk), the weapon as developed, through a multitude of small and seemingly inconsequential technical decisions, was one whose idealized use could only really be against a large urban target — a city. The scientists on the Target Committee, including Oppenheimer, were themselves enthusiastic about the possibility, and agreed that the weapon could not be effectively used against a small or purely military target. In the meeting notes, it is evident that they regarded the destruction of a large urban area containing at least one “military” (their scare quotes) facility to be the real marker of success for the weapon, apt to produce an awed and terrified reaction not only among the Japanese, but the rest of the world. The Target Committee recommended that the cities of Kyoto, Yokohama, Hiroshima, and Kokura be considered as possible targets (the final target list of Hiroshima, Kokura, Niigata, and Nagasaki was not agreed upon until late summer). 33 (No systematic consideration was made of using the weapon in the European theatre of the war, because it was clear that the war in Germany would be over by the time the bombs were ready for use. 34 )

Between these two committees, one can see both that the planning involved in the “use of the bombs” was much more than the short-term, and that several key scientists were themselves involved in some of these determinations. Bush, Conant, and Oppenheimer are in particular marked by their concern with the question of the postwar situation: all foresaw a world in which secret nuclear arms races would abound, and in which new weapons (like the hydrogen bomb and the ballistic missile) would greatly multiply the power of the weapons and their threat. Stimson was particularly convinced by such overtures, regarding the bomb as not merely a new weapon, but “as a new relationship of man to the universe,” as he opined at one Interim Committee meeting. These particular, well-connected historical actors addressed this fear with a hope for future international control of atomic energy, and believed that the best means of effecting this was to make the first use of the bomb particularly horrific, a wake-up call to the rest of the world. 35

One should not get the impression, however, that scientific perspectives were in general consulted on such policy matters. At Los Alamos, Oppenheimer worked to explicitly discourage discussions of long-term policy or even the question of the use of bombs, arguing that such matters were for political authorities to decide and not the scientific participants. (That he himself felt free to violate this notion repeatedly was, after the war, noted by several of his critics.) The high-intensity work at Los Alamos in the spring and summer of 1945 very nearly precluded such discussions in any event.

Other scientists, particularly Franck and colleagues at the University of Chicago, organized several committees for the discussion of “postwar problems,” as they put it, including the continued application of secrecy after the war (they were against it), and the need for funding postwar peaceful nuclear research (they were for it). One of these committees, on “Political and Social Problems,” penned a carefully-argued plea against the first use of the atomic bomb against a city. The Franck Report, as it was called, was considered by the Interim Committee, but opposed by Oppenheimer and several other high-ranking scientists who were consulted on the matter.

Leo Szilard, who had initially proposed the nuclear fission chain reaction and was involved in the creation of the first reactors, attempted in vain to raise substantive policy questions and was actively inhibited by the military chain of command. In short, the scientists who were in positions of influence lobbied strongly along lines that were acceptable to the military and political authorities, and the handful of others who were motivated to influence authorities in a different direction were deliberately blocked. 36

News of the successful results of the “Trinity” test was conveyed to Secretary of War Stimson and President Truman, both attending the Potsdam Conference, immediately after its detonation. By late July 1945, a strike order was drafted (by Groves) and approved (by Stimson) which specified that the “first special bomb” could be dropped “after about 3 August 1945” on one of the four approved targets. Another clause specified that, “additional bombs will be delivered on the above targets as soon as made ready by the project staff.” The weapon components were shipped to the island of Tinian in the South Pacific, along with a team of scientists and engineers who were necessary to assemble them. The 20th Air Force, led by Maj. Gen. Curtis LeMay, the architect of the firebombing campaign against Japan, aided in the logistics of “delivering” the weapons. 37

Weather conditions delayed the dropping of the first bomb, the gun-type weapon code-named “Little Boy,” over the city of Hiroshima until August 6, 1945. The mission was a success by the standards of the project: the city was completely disabled and about half of its occupants were killed, around 90% of them civilians. A coordinated “publicity” campaign was immediately launched by Manhattan Project officials to inform the world about the new weapon, including a Presidential press release and numerous newspaper stories written by a New York Times science journalist, William L. Laurence, who was “embedded” in (or co-opted by) the project. With no immediate response from the Japanese (they were, it was later discovered, verifying the truth of said statements, which was a difficult thing to do given the disruption of infrastructure caused by the bombing), and weather conditions increasingly unfavorable, the date of the second bombing attack was moved up by the forces on Tinian to August 9, 1945. This effort, using the implosion weapon code-named “Fat Man,” was more problematic: numerous errors and mishaps characterized the bombing run, with the bomb being detonated somewhat off-target on the secondary target city, Nagasaki. On August 10, 1945, Groves reported to his superiors that a third bomb would be ready for use by August 17, which resulted in the immediate order by Truman to halt further bombing until explicit Presidential authorization was given. Japan attempted to surrender with a condition (preservation of the Emperor) on August 10, which was rejected by the United States. After continued conventional bombing and a failed coup attempt, Japan surrendered unconditionally on August 14. The exact cause of surrender remains controversial: another “shocking” event, from the perspective of the Japanese high command, took place in that time period, namely the declaration of war against Japan by the previously-neutral Soviet Union, and the overwhelming Soviet invasion of Manchuria. Historians have long debated whether the atomic bombings, the Soviet invasion, or some combination of the two were responsible for the final decision to surrender, but in the Anglo-American sphere it has been common since 1945 to attribute it almost exclusively to the atomic bomb attacks, in part as an explicit justification of said attacks. 38

There have been many historical interpretations and arguments, both scholarly and popular, regarding the political decisions behind the use of the atomic bombs. Briefly, the crafters of the “orthodox” interpretation argued that the bombs were dropped exclusively to end the war as soon as possible, and were the product of a rational, deliberative process that took into account a delicate moral calculus, and had, on balance, a positive effect. Perhaps unsurprisingly, this interpretation was created very deliberately by a small group of Americans directly involved in the high-level atomic policymaking — Conant, Compton, Groves, Stimson, and Truman, among others — and was mobilized only in late 1946, when criticisms of the bombings were beginning to mount. The most important American critics from the time of the necessity of the bombings were, interestingly, high-ranking members of the US military, who felt their accomplishments were being overshadowed by a technological marvel. The various alternative (“revisionist”) positions have argued that the bombs were dropped to satisfy geopolitical concerns (e.g., to “scare Russia”), were unnecessary (e.g., the Japanese were “on the verge of surrender”), or were inhumane to the point of being war crimes (e.g., the deliberate massacre of tens of thousands of non-combatants). These debates have continued in various forms, and with various degrees of vehemence, over the decades, with a peak around the 50th anniversary of the bombings (1995), symbolized by the controversy over the Smithsonian Museum exhibit of the Enola Gay , the B-29 which dropped the bomb over Hiroshima. Both versions of the story have evidence in their favor, though both also have a tendency to “over-rationalize” a process that was in many ways quite haphazard. In general, historians of science and technology have tended to downplay the importance of high-level political deliberation, and instead emphasize the momentum that the project developed and the inordinate amount of resources consumed as it moved towards completion, making the use of the weapons almost inevitable. 39

The Manhattan Engineer District continued to exist, as an organizational entity, into the immediate postwar period. Despite the wartime attempts to streamline the question of transition into peacetime, there were significant delays. Some of these were inherent to the questions of broader nuclear policy: what should the peacetime footing of the new nuclear industry be? Should the United States proceed on a program to create more atomic bombs, and should it pursue greater innovation in their designs, or should it be angling for a world where atomic weapon development was intentionally limited through international agreements? Other delays, notably over legislation governing the domestic regulation and control of nuclear technology, were encouraged by former project scientists: a “Scientists’ Movement” formed specifically to derail the legislation proposed by the military which would, in the scientists’ eyes, maintain an undue degree of military control over atomic energy research and production. Organizations of scientists, such as the Federation of Atomic Scientists (later renamed Federation of American Scientists), composed largely of Manhattan Project veterans, engaged in lobbying Congress and the American people in favor of policies they considered crucial to avoiding a future arms race and future nuclear weapons use. Their policies were boiled down to a simple marketing mantra: “No secret, no defense, international control.” In short, an American monopoly on the atomic bomb could not be kept indefinitely in a world with arms races, no technology was likely to emerge that would render the threat of nuclear weapons impotent, and the only solution was an international treaty controlling the spread of the weapons.

The Scientists’ Movement had its one major success in pushing for the McMahon Bill, which in its initial form more closely followed their positions (but in its final form as the Atomic Energy Act of 1946 undermined many of them). The Act established a wholly civilian Atomic Energy Commission (AEC), in deliberate contrast to the military-run wartime operation. The AEC would take over all Manhattan Project operations starting in January of 1947, officially ending the Project. 40

The scientists involved in the Manhattan Project had mixed feelings about the legacy of their work. They had, in their eyes, opened up entirely new questions about the role of science in society. Even during the war, scientists at Los Alamos began to contemplate scenarios that would have previously been almost unthinkable: the ability, through the application of basic scientific discoveries, for civilization to render itself extinct. The Super, or hydrogen bomb, which had been envisioned as a possibility as early as 1941, put this in the starkest terms. At the end of the war, Los Alamos scientists calculated that while it might take the detonation of 10,000-100,000 implosion-style weapons “to bring the radioactive content of the Earth’s atmosphere to a dangerously high level,” it might require only “10 to 100 Supers” to do the same. When both the hydrogen bomb and the general question of proliferation became hot topics of debate only a few years after the war, the high level of engagement by scientists in questions of policy was seen by many as an explicit referendum on their seeming lack of concern when designing and making the first atomic bombs. The ethical questions of the “social responsibility of scientists” raised by the Manhattan Project—as well as the groundwork laid for close integration of universities and corporations in developing science useful for military applications—would resonate throughout the Cold War. 41

The Manhattan Project remains one of the prototypical examples of a massive and resource-intensive scientific-industrial-military-governmental collaboration that produced world-shattering results in an unusually short amount of time (the production phase of the project ran only 2.5 years, which is still the record for any national nuclear weapons program). As a result, there have been many invocations of the Manhattan Project as a symbol of technoscientific success: there are frequently calls for “Manhattan Projects” for things as diverse as solar power, cybersecurity, and cancer. But invoking the Manhattan Project as a symbol of intensive resource investment ignores many important factors, notably its decidedly undemocratic nature, its extensive use of militarized secrecy, its vast budget overruns, and the deep, difficult questions raised in its wake about whether it had resulted in a better or worse world.

Bibliography

Badash, Lawrence, 1995. Scientists and the Development of Nuclear Weapons: From Fission to the Limited Test Ban Treaty, 1939-1963 . Atlantic Highlands, N.J.: Humanities Press.

Barnhart, Megan, 2007. “‘To Secure the Benefits of Science to the General Welfare’: The Scientists’ Movement and the American Public during the Cold War, 1945–1960.” Ph.D. diss., University of California, Los Angeles.

Bernstein, Barton J., 1974. “The Quest for Security: American Foreign Policy and International Control of Atomic Energy, 1942-1946.” The Journal of American History 60, no. 4 (March): 1003–1044. https://doi.org/10.2307/1901011 .

Bird, Kai, and Martin J. Sherwin, 2005. American Prometheus: The Triumph and Tragedy of J. Robert Oppenheimer . New York: Knopf.

Brown, Kate, 2013. Plutopia: Nuclear Families, Atomic Cities, and the Great Soviet and American Plutonium Disasters . Oxford: Oxford University Press.

Campos, Luis A., 2015. Radium and the Secret of Life . Chicago: University of Chicago Press.

Coster-Mullen, John, 2013. Atom Bombs: The Top Secret inside Story of Little Boy and Fat Man . United States: Self-published.

De Groot, Gerard J., 2005. The Bomb: A Life . Cambridge, Mass.: Harvard University Press.

Farmelo, Graham, 2013. Churchill’s Bomb: How the United States Overtook Britain in the First Nuclear Arms Race . New York: Basic Books.

Feynman, Richard, 1986. “Surely You’re Joking, Mr. Feynman!”: Adventures of a Curious Character . New York: Bantam.

Galison, Peter, 1997. Image and Logic: A Material Culture of Microphysics . Chicago: University of Chicago Press.

Galison, Peter, and Barton Bernstein, 1989. “In Any Light: Scientists and the Decision to Build the Superbomb, 1952-1954.” Historical Studies in the Physical and Biological Sciences 19, no. 2: 267–347. https://doi.org/10.2307/27757627 .

Goldberg, Stanley, 1998. “General Groves and the Atomic West: The Making and Meaning of Hanford.” In The Atomic West , edited by Bruce W. Hevly and John M. Findlay, 39–89. Seattle: University of Washington Press.

———, 1992. “Inventing a Climate of Opinion: Vannevar Bush and the Decision to Build the Bomb.” Isis 83, no. 3 (September): 429–52. https://doi.org/10.1086/356203 .

Gordin, Michael D., 2007. Five Days in August: How World War II Became a Nuclear War . Princeton, N.J.: Princeton University Press.

Gowing, Margaret., 1964. Britain and Atomic Energy, 1939-1945 . New York: St Martin’s Press.

Groves, Leslie R., 1962. Now It Can Be Told: The Story of the Manhattan Project . New York: Harper.

Hasegawa, Tsuyoshi, 2005. Racing the Enemy: Stalin, Truman, and the Surrender of Japan . Cambridge, Mass.: Belknap Press of Harvard University Press.

Hawkins, David, Edith C. Truslow, and Ralph C. Smith, 1983. Project Y, the Los Alamos Story . Los Angeles: Tomash Publishers.

Helmreich, Jonathan E., 1986. Gathering Rare Ores: The Diplomacy of Uranium Acquisition, 1943-1954 . Princeton, N.J.: Princeton University Press.

Herken, Gregg, 2002. Brotherhood of the Bomb: The Tangled Lives and Loyalties of Robert Oppenheimer, Ernest Lawrence, and Edward Teller . New York: Henry Holt.

Hewlett, Richard G., and Oscar E. Anderson, Jr., 1962. A History of the Atomic Energy Commission . Vol. I: The new world, 1939-1946. University Park, Pennsylvania: Pennsylvania State University Press.

Hoddeson, Lillian, Paul W. Henriksen, Roger A. Meade, and Catherine Westfall, 1993. Critical Assembly: A Technical History of Los Alamos during the Oppenheimer Years, 1943-1945 . New York: Cambridge University Press.

Hounshell, David A., 1998. Science and Corporate Strategy: Du Pont R&D, 1902-1980 . New York: Cambridge University Press.

Hughes, Thomas Parke, 1989. American Genesis: A Century of Invention and Technological Enthusiasm 1870-1970 . New York, NY: Viking.

Jerome, Fred, 2002. The Einstein File: J. Edgar Hoover’s Secret War Against the World’s Most Famous Scientist. New York, NY: St. Martin’s Press.

Jones, Vincent C., 1985. Manhattan, the Army and the Atomic Bomb . United States Army in World War II. Washington, D.C.: Center of Military History, US Army.

Kemp, R. Scott, 2012. “The End of Manhattan: How the Gas Centrifuge Changed the Quest for Nuclear Weapons.” Technology and Culture 53, no. 2: 272–305. https://doi.org/10.1353/tech.2012.0046 .

Kevles, Daniel J., 1987. The Physicists: The History of a Scientific Community in Modern America . Cambridge, Mass.: Harvard University Press.

Kiernan, Denise, 2013. The Girls of Atomic City: The Untold Story of the Women Who Helped Win World War II . New York, NY: Simon & Schuster.

Kohn, Richard H., 1996. “History and the Culture Wars: The Case of the Smithsonian Institution’s Enola Gay Exhibition.” Journal of American History 82, no. 3: 1036–63.

Kragh, Helge, 1999. Quantum Generations: A History of Physics in the Twentieth Century . Princeton, N.J.: Princeton University Press.

Leslie, Stuart W., 1993. The Cold War and American Science: The Military-Industrial-Academic Complex at MIT and Stanford . New York: Columbia University Press.

Malloy, Sean L., 2007. “‘The Rules of Civilized Warfare’: Scientists, Soldiers, Civilians, and American Nuclear Targeting, 1940 – 1945.” Journal of Strategic Studies 30, no. 3 (June): 475–512. https://doi.org/10.1080/01402390701343482 .

Manhattan District History, 2013 [1947] . Washington, D.C.: US Department of Energy, Office of History and Heritage Resources. https://www.osti.gov/opennet/manhattan_district.jsp .

Nobile, Philip, 1995. Judgment at the Smithsonian . New York: Marlowe & Co.

Norris, Robert S., 2002. Racing for the Bomb: General Leslie R. Groves, the Manhattan Project’s Indispensable Man . South Royalton, Vt.: Steerforth Press.

Reed, Bruce Cameron, 2014. The History and Science of the Manhattan Project . Berlin, Heidelberg: Springer.

———, 2015. The Physics of the Manhattan Project . 3rd ed. Berlin, Heidelberg: Springer.

Rhodes, Richard, 1986. The Making of the Atomic Bomb . New York: Simon and Schuster.

Schwartz, Rebecca Press, 2008. “The Making of the History of the Atomic Bomb: Henry DeWolf Smyth and the Historiography of the Manhattan Project.” Ph.D. diss., Princeton University.

Sherwin, Martin J., 1987. A World Destroyed: Hiroshima and the Origins of the Arms Race . New York: Vintage Books.

Smith, Alice Kimball, 1965. A Peril and a Hope: The Scientists’ Movement in America, 1945-47 . Chicago: University of Chicago Press.

Smyth, Henry DeWolf, 1946. Atomic Energy for Military Purposes: The Official Report on the Development of the Atomic Bomb under the Auspices of the United States Government, 1940-1945 . Princeton: Princeton University Press.

Szasz, Ferenc Morton, 1984. The Day the Sun Rose Twice: The Story of the Trinity Site Nuclear Explosion, July 16, 1945 . Albuquerque: University of New Mexico Press.

Thorpe, Charles, 2006. Oppenheimer: The Tragic Intellect . Chicago: University of Chicago Press.

Walker, J. Samuel, 2016. Prompt and Utter Destruction: Truman and the Use of Atomic Bombs against Japan . 3rd ed. Chapel Hill: University of North Carolina Press.

———, 2005. “Recent Literature on Truman’s Atomic Bomb Decision: A Search for Middle Ground.” Diplomatic History 29, no. 2: 311–334. https://doi.org/10.1111/j.1467-7709.2005.00476.x .

Walker, Mark, 1989. German National Socialism and the Quest for Nuclear Power, 1939-1949 . New York: Cambridge University Press.

———, 1995. Nazi Science: Myth, Truth, and the German Atomic Bomb . New York: Plenum Press.

Weart, Spencer R., 2012. The Rise of Nuclear Fear . Cambridge, Mass.: Harvard University Press.

Wellerstein, Alex, 2010. “Knowledge and the Bomb: Nuclear Secrecy in the United States, 1939-2008.” Ph.D. diss., Harvard University.

———, 2008. “Patenting the Bomb: Nuclear Weapons, Intellectual Property, and Technological Control.” Isis 99, no. 1: 57–87. https://doi.org/10.1086/587556 .

In particular, a letter to President Franklin D. Roosevelt signed by Albert Einstein and warning of potential German development of atomic bombs has been central to the official histories, to the point of distorting both the letter’s contents (which do not argue for building, much less using, an atomic bomb) and its impact (it was less directly important to the making of the bomb than is often implied). To put the reasons for its prominence simply, if Einstein was in favor of something, who would dare oppose it? That Einstein was deliberately excluded from the Manhattan Project as a security risk makes for a somewhat bitter irony. See Jerome 2002. ↩

For examples of a physics-driven narrative, see Rhodes 1986; De Groot 2005; Badash 1995; Kevles 1987; and Smyth 1946. See also Kragh 1999, esp. chapter 18. ↩

E.g., Hughes 1989, chapter 5; Hounshell 1988, chapter 16; Reed 2014; Hewlett and Anderson 1962; Weart 2012; Campos 2015. ↩

The recently-declassified Manhattan District History is the source of immensely useful details on the operation of the project; see Wellerstein 2014 for contextual notes and copies of the files. Personnel figures come from Manhattan District History , Book 1, Volume 8 (“Personnel”), notably figures in Appendix A (charts 1, 1.1, and 6). The figures for 1943 were cited by a skeptical James Byrnes, head of the Office of War Mobilization, in an attempt to learn more about the project: James Byrnes to Henry Stimson (11 September 1943), Harrison-Bundy File, Roll 1, Target 8, Folder 8, “Manhattan (District) Project.” On the electrical supply, see Reed 2014, on 203; on patents, see Wellerstein 2008, on 78-79; on secrecy, see Wellerstein 2010. ↩

On the influence of science fiction imagery for early advocates of the effort, notably the work of H.G. Wells, which influenced both scientists and politicians, see Rhodes 1986, Farmelo 2013, and Weart 2012. ↩

Goldberg 1998, Groves 1962. ↩

Rhodes 1986, Hewlett and Anderson 1962, Weart 1976, Weart 2012, Kragh 1999. ↩

Walker 1989, Walker 1995, Weart 1976, Rhodes 1986, Gowing 1964, Farmelo 2013. ↩

Manhattan District History, Book 1, Volume 5 (“Fiscal Procedures”), Appendix B, table 3. ↩

Walker 1989, esp. chapter 2. ↩

Hewlett and Anderson 1962, Goldberg 1992. ↩

Rhodes 1986, Farmelo 2013. ↩

Hewlett and Anderson 1962, Reed 2014. ↩

Ibid. On the creation of the Manhattan Engineer District, see Jones 1985 and Norris 2002. The project had several code-names in the early days, including the Development of Substitute Materials, but in the end the blandness of the geographic nomenclature was appealing from a security standpoint. ↩

Reed 2015. ↩

On the various methods, see Jones 1985, chapters 6-8. ↩

On centrifuges, see Kemp 2012. On the other enrichment, see Reed 2015, chapter 5. For cost breakdowns of specific programs (here and elsewhere), see Hewlett and Anderson 1962, appendix 2. ↩

Jones 1985, chapters 6-8; Kiernan 2013. ↩

Jones 1985, chapter 9. Reed 2014 also contains an excellent overview of the technical processes, and Reed 2015 goes into even more depth. Personnel figures come from Manhattan District History , Book 1, Volume 8 (“Personnel”), notably figures in Appendix A (charts 1, 1.1, and 6). ↩

The 225-gram figure comes from Hanford Site History of Operations, 1 January 1944-20 March 1945, Book 4, Nuclear Testing Archive, Las Vegas, Nevada, document NV0716547: https://www.osti.gov/opennet/detail.jsp?osti-id=905678 . The Nuclear Testing Archive, available through the Department of Energy’s OpenNet website, is an immensely useful collection of records related to the American wartime and Cold War nuclear program. ↩

Findlay and Hevly 2011; Brown 2013. ↩

Norris 2002; Groves 1962, quote on 140. ↩

Bird & Sherwin 2005, Herken 2002, Thorpe 2006; data on staff at Los Alamos comes from Hawkins et al. 1983, on 484. ↩

Hoddeson et al. 1993; Schwartz 2008; Galison 1997, chapter 4; on the distribution of scientists by discipline, see the division graph in Hawkins et al. 1983, on 487. ↩

Hewlett and Anderson 1962. Of the memoirs, none demonstrates this disconnect in tone more than Feynman 1986. ↩

Hoddeson et al. 1993, chapters 7 and 13. ↩

Hoddeson et al. 1993, chapters 7 and 13; see also Reed 2014 and Reed 2015. ↩

Manhattan District History covers most of this far-flung work. On American efforts to acquire uranium during the war, see Helmreich 1986. Total uranium comes from Manhattan District History , Book 5, Volume 6 (“Electromagnetic Project – Operations”), Top Secret Appendix; plutonium data comes from C.S. Garner, “49 Interim Processing Program No. 24,” (30 August 1945), DOE OpenNet Document ALLAOSTI126018: https://www.osti.gov/opennet/detail.jsp?osti-id=896738 . ↩

Szasz 1984. ↩

Gordin 2007; Coster-Mullen 2013. Coster-Mullen’s book, though self-published (and constantly being updated), contains a wealth of primary sources, notes, and detailed information about the construction and deployment of the first atomic bombs. ↩

Hewlett and Anderson 1962, chapters 10-11; Sherwin 1987; Smith 1965. ↩

Malloy 2007. ↩

According to Groves’ later recollection, Roosevelt expressed some interest in using the weapon against Germany in December 1944. However, no weapons were yet available. See Norris 2002, 334. ↩

Sherwin 1987, with Stimson’s quote on 296. ↩

Smith 1965, Badash 1995, Norris 2002. ↩

Gordin 2007, Coster-Mullen 2013, Hasegawa 2005. ↩

Coster-Mullen 2013, Wellerstein 2010, Gordin 2007, Weart 2012, Walker 2005, Hasegawa 2005. ↩

Walker 2005, Walker 2016, Nobile 1995, Kohn 1996. For those who emphasize the “momentum” of the project, see Goldberg 1998, Gordin 2007, and Malloy 2007. ↩

Bernstein 1974, Hewlett and Anderson 1962, Smith 1965, Barnhart 2007. ↩

Manhattan District History , Book 8, Volume 2 (“Los Alamos–Technical”), on XIII-10. On the H-bomb, see Galison and Bernstein 1989. On later work and controversies, see, e.g., Leslie 1993. ↩

Alex Wellerstein, "Manhattan Project," Encyclopedia of the History of Science (April 2019), accessed 24 August 2024. https://doi.org/10.34758/swph-yq79 .

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Manhattan Project

By: History.com Editors

Updated: July 21, 2023 | Original: July 26, 2017

The Manhattan Project was the code name for the American-led effort to develop a functional atomic weapon during World War II. The controversial creation and eventual use of the atomic bomb engaged some of the world’s leading scientific minds, as well as the U.S. military—and most of the work was done in Los Alamos, New Mexico, not the borough of New York City for which it was originally named.

The Manhattan Project was started in response to fears that German scientists had been working on a weapon using nuclear technology since the 1930s—and that Adolf Hitler was prepared to use it.

America Declares War

The agencies leading up to the Manhattan Project were first formed in 1939 by President Franklin D. Roosevelt after U.S. intelligence operatives reported that scientists working for Adolf Hitler were already working on a nuclear weapon.

At first, Roosevelt set up the Advisory Committee on Uranium, a team of scientists and military officials tasked with researching uranium’s potential role as a weapon. Based on the committee’s findings, the U.S. government started funding research by Enrico Fermi and Leo Szilard at Columbia University , which was focused on radioactive isotope separation (also known as uranium enrichment) and nuclear chain reactions.

The Advisory Committee on Uranium’s name was changed in 1940 to the National Defense Research Committee, before finally being renamed the Office of Scientific Research and Development (OSRD) in 1941 and adding Fermi to its list of members.

That same year, following the Japanese attack on Pearl Harbor , President Roosevelt declared that the U.S. would enter World War II and align with Great Britain, France and Russia to fight against the Germans in Europe and the Japanese in the Pacific theater.

The Army Corps of Engineers joined the OSRD in 1942 with President Roosevelt’s approval, and the project officially morphed into a military initiative, with scientists serving in a supporting role.

The Manhattan Project Begins

The OSRD formed the Manhattan Engineer District in 1942 and based it in the New York City borough of the same name. U.S. Army Colonel Leslie R. Groves was appointed to lead the project.

Fermi and Szilard were still engaged in research on nuclear chain reactions, the process by which atoms separate and interact, now at the University of Chicago , and successfully enriching uranium to produce uranium-235.

Meanwhile, scientists like Glenn Seaborg were producing microscopic samples of pure plutonium, and Canadian government and military officials were working on nuclear research at several sites in Canada.

On December 28, 1942, President Roosevelt authorized the formation of the Manhattan Project to combine these various research efforts with the goal of weaponizing nuclear energy. Facilities were set up in remote locations in New Mexico , Tennessee and Washington , as well as sites in Canada, for this research and related atomic tests to be performed.

The Unsung African American Scientists of the Manhattan Project

At least 12 Black chemists and physicists worked as primary researchers on the team that developed the technology behind the atomic bomb.

The Trinity Test

In the early 1940s, the U.S. government authorized a top‑secret program of nuclear bomb testing and development, codenamed “The Manhattan Project.”

J. Robert Oppenheimer: 5 Facts About the ‘Father of the Atomic Bomb’

The theoretical physicist read Sanskrit, loved horseback riding in New Mexico and was targeted during the Red Scare.

Robert Oppenheimer and Project Y

Theoretical physicist J. Robert Oppenheimer was already working on the concept of nuclear fission (along with Edward Teller and others) when he was named director of the Los Alamos Laboratory in northern New Mexico in 1943.

Los Alamos Laboratory—the creation of which was known as Project Y—was formally established on January 1, 1943. The complex is where the first Manhattan Project bombs were built and tested.

On July 16, 1945, in a remote desert location near Alamogordo, New Mexico, the first atomic bomb was successfully detonated—the Trinity Test —creating an enormous mushroom cloud some 40,000 feet high and ushering in the Atomic Age.

Scientists working under Oppenheimer had developed two distinct types of bombs: a uranium-based design called “the Little Boy” and a plutonium-based weapon called “the Fat Man.” With both designs in the works at Los Alamos, they became an important part of U.S. strategy aimed at bringing an end to World War II.

The Potsdam Conference

With the Germans sustaining heavy losses in Europe and nearing surrender, the consensus among U.S. military leaders in 1945 was that the Japanese would fight to the bitter end and force a full-scale invasion of the island nation, resulting in significant casualties on both sides.

On July 26, 1945, at the Potsdam Conference in the Allied-occupied city of Potsdam, Germany, the U.S. delivered an ultimatum to Japan—surrender under the terms outlined in the Potsdam Declaration (which, among other provisions, called for the Japanese to form a new, democratic and peaceful government) or face “prompt and utter destruction.”

As the Potsdam Declaration provided no role for the emperor in Japan’s future, the ruler of the island nation was unwilling to accept its terms.

Hiroshima and Nagasaki

Meanwhile, the military leaders of the Manhattan Project had identified Hiroshima , Japan, as an ideal target for an atomic bomb, given its size and the fact that there were no known American prisoners of war in the area. A forceful demonstration of the technology developed in New Mexico was deemed necessary to encourage the Japanese to surrender.

With no surrender agreement in place, on August 6, 1945, the Enola Gay bomber plane dropped the as-yet untested “Little Boy” bomb some 1,900 feet above Hiroshima, causing unprecedented destruction and death over an area of five square miles. Three days later, with still no surrender declared, on August 9th, the “Fat Man” bomb was dropped over Nagasaki , the site of a torpedo-building plant, destroying more than three square miles of the city.

The two bombs combined killed more than 100,000 people and leveled the two Japanese cities to the ground.

The Japanese informed Washington, which following Roosevelt’s death was under the new leadership of President Harry Truman , of their intention to surrender on August 10th, and formally surrendered on August 14, 1945.

Legacy of the Manhattan Project

With the development of weapons designed to bring about the end of World War II as its stated mission, it’s easy to think that the story of the Manhattan Project ends in August 1945. However, that’s far from the case.

Following the end of the war, the United States formed the Atomic Energy Commission to oversee research efforts designed to apply the technologies developed under the Manhattan Project to other fields.

Ultimately, in 1964, then-President Lyndon B. Johnson put an end to the U.S. government’s effective monopoly over nuclear energy by allowing for private ownership of nuclear materials.

The nuclear fission technology perfected by the Manhattan Project engineers has since become the basis for the development of nuclear reactors, power generators, as well as other innovations, including medical imaging systems and radiation therapies for various forms of cancer.

Manhattan: The Army and the Atomic Bomb. U.S. Army Center of Military History . The Manhattan Project—Its Story. U.S. Department of Energy: Office of Scientific and Technical Information . Leo Szilárd, a traffic light and a slice of nuclear history. Scientific American . J. Robert Oppenheimer (1904—1967). Atomic Archive .

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The Manhattan Project

Written by: edward g. lengel, the national world war ii museum, by the end of this section, you will:.

• Explain the causes and effects of the victory of the United States and its allies over the Axis Powers

Suggested Sequencing

Use this narrative with the Dropping the Atomic Bomb Decision Point and the Was the Use of the Atomic Bomb Justified? DBQ Lesson to show the development of the United States’ nuclear program and subsequent use in the Hiroshima and Nagasaki bombings.

Fundamental discoveries about the nature of the atom took place during the most war-torn century in human history. By the 1920s and 1930s, scientists were intensively studying the military ramifications of atomic power. In 1938, German chemist Otto Hahn scored a breakthrough by not only splitting the uranium atom but also discovering the immense explosive potential of the process. He and other German scientists immediately moved on to focus their research on creating an atomic bomb for the Nazi state.

Scientists in other nations quickly became aware of the German work in this field and initiated atomic programs of their own. Nuclear research in Britain, led by German scientists who had fled the Nazi regime, surged ahead with the discovery that it would be possible to build a bomb with only small quantities of the rare isotope uranium-235. Lacking this knowledge, and assuming it would take many years to acquire the supplies necessary to build a bomb, German scientists had slowed their work by the early 1940s. But other scientists did not know this. On August 2, 1939, famed scientist Albert Einstein wrote to President Franklin Roosevelt urging him to accelerate his country’s atomic program to ensure that the Germans did not develop the bomb first.

An alarmed Roosevelt responded energetically, especially after the Japanese attack on Pearl Harbor and the American entry into World War II in Europe and Asia. Led by his scientific advisors to believe that, with great effort, an atomic weapon could be developed by 1944, on June 17, 1942, the president initiated the atomic program that came to be called the Manhattan Project. Unlike the Germans, who assumed they would win the war quickly and that continuing their atomic program was thus not worth the trouble, the Americans and British anticipated a long conflict and so were deeply committed to their projects. They shared information with each other along the way, but not with the Soviet Union. Soviet espionage nevertheless monitored the Anglo-American programs with a degree of success that was not known until many years later.

The Manhattan Project, named after a supervisory district of the U.S. Army Corps of Engineers in Manhattan, New York, oversaw the U.S. atomic program. It was headed by General Leslie R. Groves and carried out its work at facilities in Illinois, Tennessee, Washington state, and New Mexico ([link]Figure_12_03_ManProjMap[/link]). Progress was rapid, thanks not just to scientific work but to America’s vast industrial capacity. In December 1942, scientists Enrico Fermi and Arthur Compton created the first-ever uranium chain reaction in the basement of the University of Chicago’s football stadium. In a facility built the following year on a mesa at Los Alamos, New Mexico, meanwhile, scientist J. Robert Oppenheimer and his team worked to create the first atomic bomb.

(a) Enrico Fermi, one of the Manhattan Project scientists, created the first nuclear reactor, the Chicago Pile-1. (b) Important sites associated with the Manhattan Project were scattered across the country.

The expenses of the top-secret Manhattan Project were concealed from Congress, subsumed in appropriations for the War Department. By the time the war ended, they totaled approximately $2 billion, dwarfing every other wartime military project except the creation of the B-29 Superfortress bomber. Roosevelt ensured that his atomic scientists were never short of funds, however, knowing that if the project succeeded, no one would question the cost.

The first bomb was nearly complete at the time of President Roosevelt’s death on April 12, 1945. New president Harry S. Truman ordered the program to move forward despite Germany’s impending surrender, with a view toward possibly using the weapon against Japan. While the interim committee Truman created considered the military, political, and moral advisability of using the bomb, Oppenheimer’s team completed the first-ever atomic weapon and prepared it for testing.

The test, codenamed “Trinity,” took place on July 16, 1945, in the desert at Alamogordo, New Mexico, 200 miles south of Los Alamos. The device, mounted on a metal tower, consisted of just 13.5 pounds of plutonium encased in two-and-a-half tons of explosives. It exploded at 5:29 a.m. to devastating effect, equal to the detonation of almost 20,000 tons of TNT. Groves and Oppenheimer witnessed the atomic fireball expand into a mushroom cloud visible 60 miles away. Horrified by what he saw, Oppenheimer called to mind words from the Bhagavad Gita: “Now I am become Death, the destroyer of worlds.” But it was too late to turn back. The world had entered the nuclear age.

(a) In 1945, the mushroom cloud from the first atomic weapon test, “Trinity,” could be seen as far as 60 miles away. (b) J. Robert Oppenheimer and General Leslie Groves inspect the aftermath of the explosion at Alamogordo, New Mexico, in July 1945.

On August 6, the Enola Gay , a B-29 Superfortress, dropped the uranium bomb nicknamed Little Boy, which exploded with the force of 12,500 tons of TNT 1,900 feet above the Japanese city of Hiroshima. With a blinding flash and rising mushroom cloud, the blast and resulting firestorm obliterated the city and destroyed 70,000 buildings. People were vaporized from the blast and their shadows imprinted on walls. An estimated 70,000 to 80,000 civilians and soldiers were immediately killed, and thousands later died of radiation poisoning and burns. Tormented survivors were disfigured with hanging skin and burns. President Truman sent public messages announcing the dropping of an atomic bomb and threatened more if Japan refused to surrender. Still, the Japanese government fought on.

On August 9, another B-29 bomber dropped a plutonium bomb called Fat Man on Nagasaki, with an even larger blast equivalent to 22,000 tons of TNT. Due to significant cloud cover this second bomb missed its target by a wide margin, somewhat limiting its destructive impact. Nevertheless, it killed at least 30,000 people and caused suffering for thousands of survivors. Over the next five days, conventional bombings of other major cities killed an additional 15,000 Japanese. Finally, on August 14, Japan surrendered and World War II ended.

The development of the atomic bomb and the ensuing arms race between the United States and the Soviet Union, along with their allies, ushered in the nuclear age and imperiled all humanity. Although the only atomic bombs ever used were those dropped on Hiroshima and Nagasaki during World War II, the Cold War led to the credible threat of their additional use and the fear of widespread destruction.

Review Questions

1. The costs associated with the Manhattan Project did not lead to protest primarily because

• Congress considered the costs to be justified
• President Roosevelt overruled any objections
• atomic bombs were inexpensive to build
• they were concealed from Congress

2. The atomic explosion at Alamogordo, New Mexico, on July 16, 1945

• failed to produce the desired results
• ended World War II
• proved the success of the Manhattan Project
• convinced President Truman the atomic bomb was too powerful to use

3. Development of the atomic bomb in the United States during the 1940s occurred

• at various locations throughout the United States
• primarily in Manhattan, New York
• exclusively under civilian leadership
• primarily using the research generated by American scientists

4. The American scientist who oversaw the Manhattan Project was

• Leslie Groves
• Robert Oppenheimer
• Enrico Fermi

5. The scientific advances behind the Manhattan Project primarily benefited from

• the work of émigré scientists from totalitarian regimes
• Anglo-American military cooperation
• American anticipation of a short military conflict
• exchange of nuclear scientific knowledge between the United States and the Soviet Union

Free Response Questions

• Analyze the factors that led the United States to build the first atomic bomb.
• Describe the organization of the Manhattan Project.

AP Practice Questions

“Sir: Some recent work by E. Fermi and L. Szilard . . . leads me to expect that the element uranium may be turned into a new and important source of energy in the immediate future. . . . I believe therefore that it is my duty to bring to your attention the following facts and recommendations. . . . It may be possible to set up a nuclear chain reaction in a large mass of uranium . . . This new phenomenon would also lead to the construction of bombs . . . A single bomb of this type, carried by boat and exploded in a port, might very well destroy the whole port together with some of the surrounding territory. However, such bombs might very well prove too heavy for transportation by air. . . . In view of this situation you may think it desirable to have some permanent contact maintained between the Administration and the group of physicists working on chain reactions in America.”

Albert Einstein, Letter to President Franklin Roosevelt, August 2, 1939

1. The sentiments expressed in the excerpt most directly led to the

• creation of the Manhattan Project
• implementation of the island-hopping strategy
• D-Day invasion
• defeat of Nazi Germany

2. Which group would most likely support the argument made in the excerpt?

• Critics of the military-industrial complex
• Opponents of the Treaty of Versailles
• Proponents of the Lend-Lease Act
• Isolationists such as the America First group

3. This excerpt was written in response to the

• federal programs created by the New Deal
• rise of fascism in Europe
• debates about the morality of using atomic weapons
• expansion of communist ideology in Southeast Asia

Primary Sources

Einstein, Albert. 1939 letter to President Roosevelt. http://www.fdrlibrary.marist.edu/archives/pdfs/docsworldwar.pdf

“Trinity Test Eyewitnesses.” Atomic Heritage Foundation . https://www.atomicheritage.org/key-documents/trinity-test-eyewitnesses

Suggested Resources

Bird, Kai, and Martin J. Sherwin. American Prometheus: The Triumph and Tragedy of J. Robert Oppenheimer . New York: Knopf, 2005.

Chambers, John Whiteclay, ed. The Oxford Companion to American Military History . Oxford, UK: Oxford University Press, 1999.

Conant, Jennet. 109 East Palace: Robert Oppenheimer and the Secret City of Los Alamos . New York: Simon and Schuster, 2005.

Kelly, Cynthia C., ed. Manhattan Project: The Birth of the Atomic Bomb in the Words of its Creators, Eyewitnesses, and Historians . New York: Black Dog & Leventhal, 2009.

Kunetka, James. The General and the Genius: Groves and Oppenheimer – The Unlikely Partnership that Built the Atom Bomb . New York: Regnery, 2015.

Rhodes, Richard. The Making of the Atomic Bomb . New York: Simon and Schuster, 1987.

Weinberg, Gerhard L. A World at Arms: A Global History of World War II . Cambridge, UK: Cambridge University Press, 1994.

Related Content

Life, Liberty, and the Pursuit of Happiness

In our resource history is presented through a series of narratives, primary sources, and point-counterpoint debates that invites students to participate in the ongoing conversation about the American experiment.

The Manhattan Project and the Experiment That Changed the World

“now i am become death, the destroyer of worlds.”.

John Loeffler

US Department of Energy

A mushroom cloud is one of the most terrifying images imaginable for billions of people around the world who still live under the specter of a nuclear war, but for many others, it was the fulfillment of one of the most consequential research efforts in human history: the Manhattan Project.

Under the codename Manhattan Project, the US effort in World War II to beat Nazi Germany to an atomic weapon had a complicated and unquestionably terrible legacy. This is especially true for the people of Japan, the only nation that has ever suffered a nuclear attack.

While many notable scientists involved in the Manhattan Project would experience anguish, guilt, and horror over the consequences of their work, others saw the atomic bomb — and the doctrine of Mutually Assured Destruction (MAD) that accompanied it — as the only way to secure lasting peace in the world.

No matter one’s ultimate position on the issue of the atomic bombs that ended the Second World War, there is no question that few research projects have proven as consequential for human history as the Manhattan Project.

Early Atomic Theory

The idea of an indivisible unit of matter is an ancient idea going back to some of the earliest Greek and Indian texts on record, but some of the first to describe the concept of the atom were the ancient Greek philosophers Leucippus and Democritus, in the fifth century BCE.

The name atom itself comes from the ancient Greek word atomos , which roughly means “uncuttable”, and for about three millennia, the indivisibility of the atom was more of a philosophical position than a scientific one.

In the Middle Ages, questions about the true nature of matter straddled the line between practical sciences and the practice of alchemy. European and Islamic scientists and philosophers picked up where Greek philosophers left off. Sometime around 1000 AD, bismuth was discovered by  Persian alchemist  Jabir ibn Hayyan and in 1669,  German alchemist Hennig Brand discovered phosphorus while trying to create the philosopher’s stone, a legendary substance that was believed to turn metal into gold.

Even such scientific luminaries as Sir Isaac Newton  could not help but dabble in alchemy, but it wasn’t until the 18th and 19th centuries that atomic theory as we know it today was put on a more solid scientific footing. 

After scientists like the 18th-century French chemist  Antoine-Laurent Lavoisier began to isolate and identify individual elements like oxygen, John Dalton  (1766-1844) developed his atomic theory.

Dalton claimed that atoms of different elements vary in size and mass, which refuted the long-held notions  that atoms of all kinds of matter are alike. Dalton  formulated a method of measuring the masses of various elements according to the way they combined with fixed masses of each other.

Nuclear physics was born when  Ernest Rutherford split the atom in 1917 . Then, one of the most consequential discoveries in physics came in December 1938 when  physicists Lise Meitner, Otto Hahn, Fritz Strassmann, and Otto Frisch worked out that bombarding a uranium atom with neutrons broke the atom into two smaller components.

These elements combined had only four-fifths the atomic weight of the original uranium atom, so using Einstein’s equation E = mc 2 , Meitner and Frisch were able to show that the missing fifth was released as energy (200 MeV, to be exact). The physicists had discovered nuclear fission, just as the shadow of war descended over Europe in 1939. 

The Outbreak of World War II

After the discovery of nuclear fission, it was quickly understood that nuclear fission in a large amount of uranium could produce a cascading chain reaction that would release an incredible amount of energy.

The military applications of this were obvious, and it wasn’t long before Germany began its  Uranverein — or “ uranium club “.  The program began in April 1939, five months before the Nazis invaded Poland and touched off the Second World War.

Once the war began, physicists fleeing Europe immediately feared what the Nazis would do if they were the first to create an atomic bomb. Among them was Albert Einstein , who signed onto a letter sent to President Franklin D. Roosevelt in August 1939 to alert the US government of Nazi Germany’s suspected nuclear program, and to plead with the US to begin securing uranium stockpiles around the world.

The letter also implored the government to invest in the research of nuclear fission chain reactions being carried out by Enrico Fermi in the United States.

Roosevelt ordered government officials to follow up on the letter and judge the feasibility of developing weapons based on nuclear fission chain reactions. They came back to affirm that not only was it theoretically possible but that such weapons would be by far the most powerful weapons humanity had ever seen.

Beginning the Manhattan Project

Considering the stakes, the initial investment into what would be known as the Manhattan Project — the US Army office that worked on the project was originally located in Manhattan, NY — was pretty modest.

The US Navy granted Columbia University $6,000 to fund Fermi’s research into fission chain reactions. Fermi, along with Leo Szilard, Eugene Booth, John Dunning, and others, used the funding to purchase graphite and subsequently produced the first fission reaction in the US.

Soon, the US government began to increase funding into uranium and plutonium fission reactions, but still at a relatively small scale.

In the UK, Frisch and Rudolf Peierls identified the amount of uranium required to produce a fission chain reaction, a “critical mass” of about 20 lbs (9.07 kg). This made the amount of material required small enough to fit on a conventional bomber, so when they presented this data to the UK government, it approved its own atomic weapons program.

By late 1941, the UK was further along in its atomic weapons research than the US, so the two countries began exchanging atomic weapons research to help accelerate their development even before the US formally entered the war. 

Roosevelt put the US Army in charge of the program, due to that branch’s experience with large-scale research efforts, and once the US entered the war in December 1941 after the bombing of Pearl Harbor, investment in the Manhattan Project began in earnest.

US officials tapped University of California theoretical physicist J. Robert Oppenheimer to head up “Project Y”, the part of the Manhattan Project that would actually design and build the atomic bomb itself. Oppenheimer had no experience leading the kind of laboratory that the project would need, but many of the other candidates being considered were working on other projects where they couldn’t be spared.

He also had some personal connections to known communists, including both his wife and suspected mistress, which raised security concerns. These were assuaged, however, after interviews with Oppenheimer, and he was given the lead on developing the US atomic bomb. ( In 1954, Oppenheimer was called before a tribunal of the Atomic Energy Commission for a hearing on his past involvement with communist organizations and the possibility that he was a Soviet spy. As a result of evidence given, his security clearance was revoked, provoking outrage.)

The scale of the project was truly enormous, involving over a dozen sites around the US with material — especially Uranium — sourced from both Canada and the Belgian Congo. 

Oppenheimer suggested a site near the Los Alamos Ranch, next to the Sangre de Cristo mountains in New Mexico, for the laboratory for Project Y. The site chosen would come to be called the Los Alamos National Laboratory, though it was listed as “Site Y” or “The Hill” in official documents, given the top-secret nature of the project. 

Sites Contributing to the Work at Los Alamos Laboratory

For secrecy and practicality’s sake, the Manhattan Project was distributed across several different locations across the United States and Canada.

One of the most important of these sites was the Clinton Engineer Works in Oak Ridge, Tennessee. Here, the uranium isotope needed to make the first atomic bomb was isolated and extracted into a purer mass of material.

The challenge is that the uranium mined in Canada and the Belgian Congo was about 99.3% uranium-238, and 0.7% uranium-235. Only uranium-235 was used as fissile material, so it needed to be separated or “enriched” to produce a critical mass for a bomb.

Enriched Uranium-235 was produced at two separate plants at Oak Ridge, each of which used a separate method for obtaining the U-235, and delivered to the Los Alamos Laboratory by July 1945. Almost all the U-235 produced at Oak Ridge, 64 kg, was used to create the Little Boy atomic bomb.

Part of the strategy of the Manhattan Project was not to invest everything into uranium fission. Plutonium-239, which had only just been discovered in late 1940-early 1941 at the University of California, Berkeley, was also developed as a fissile material for an atomic bomb.

It has a much lower critical mass than uranium-235, but it isn’t easily found in nature. Instead, the easiest way to produce plutonium-239 was to bombard uranium-238 with deuterons, an isotope of hydrogen.

The uranium would absorb neutrons in the bombardment and produce neptunium-239, which would decay into plutonium-239. 

The easiest way to do this is in nuclear reactors using uranium-235 as fuel rods. During the Manhattan Project, several such reactors were built to produce the plutonium needed to construct an atomic bomb, including the X-10 graphite reactor at the Clinton Engineer Works in Oak Ridge and at the Hanford Engineer Works in Washington state.

Since plutonium-239 reaches a critical mass at about 24 lbs — which roughly forms a sphere with a four-inch diameter (10.6 cm) — it doesn’t need as much material to create the chain fission reaction needed for a bomb. The trouble was producing and isolating enough of the isotope from the reactors to reach the required mass.

Uranium can be extracted from an ore that was mined, but you had to effectively spend uranium to get plutonium, so there was a careful balance that had to be struck to ensure there was enough of both fissile materials for the Manhattan Project’s purposes.

In total, enough plutonium was delivered to Los Alamos by July 1945 to produce two atomic bombs. In total, the Manhattan Project produced enough fissile material by 1945 for just three bombs, and no one was even sure if any of them would work. 

Designing the World’s Most Powerful Weapon

There were two different designs used to produce an atomic bomb. 

The first was what is known as a gun-type bomb . This method involves “shooting” a slug of sub-critical fissile material into a target sub-critical mass of the same fissile material, using a conventional chemical charge as a propellant.

When the fissile slug hits the target mass, it shoots a burst of neutrons into it to initiate a supercritical fission reaction that would grow exponentially through both slug and target masses. 

The key challenge with this type of device is to achieve supercriticality before the bomb destroys itself. This means that the speed and mass of the slug need to be enough to initiate the chain reaction quickly but not so big or fast that it destroys the two masses before they have sufficient time to undergo supercritical fission reactions.

This type of bomb is easier to produce, however, so it was the first type of bomb planned at Los Alamos in 1943.

Thin Man, as the bomb was called, used plutonium as its reactant. However, after Los Alamos Laboratory received its first batch of plutonium-239 from Oak Ridge in 1944, it was found that there was too much plutonium-240 in the mass to be used in a gun-type bomb.

In a gun-type bomb, the plutonium-240 would react too fast and it would blow apart the bomb before the rest of the material had achieved a sufficient critical reaction to trigger the desired explosion.

In order to use the plutonium material, another bomb design had to be developed.

A Los Alamos physicist, Seth Neddermeyer, had already been working on plans for an implosion-type bomb in 1944. Implosion uses spherically-arranged explosives to compress a subcritical mass of fissile material into denser mass.

As the atoms of the subcritical mass squeeze together, neutron capture happens much quicker and quickly initiates the supercritical fission chain reaction.

The problem with an implosion-type bomb is that it is a much more sophisticated design from a theoretical and practical perspective, which made it much harder to actually implement.

This design, however, had the advantage of largely negating the problem of premature plutonium-240 detonation , since the explosive force that isotope produces is being counteracted by the implosive force that triggered its reaction in the first place.

In late 1943, John von Neumann, a mathematician and computer scientist at Los Alamos Laboratory improved on Neddermeyer’s implosion design by refining the calculations needed to generate the right implosive detonation and also introduced a spherical design for the plutonium core, rather than a cylinder as Neddermeyer’s design called for.

The spherical design greatly reduced the chance of premature detonations while also increasing the efficiency of the fissile chain reaction by keeping it tightly packed for a longer duration. This increased the number of fission reactions achieved in the plutonium before the energy being released blew the bomb apart.

Satisfied that implosion was the better of the two designs, Oppenheimer redirected Los Alamos’ efforts toward building a new bomb called Fat Man, which would use the plutonium they already had to produce the first atomic bomb. 

Von Neumann’s design used explosive “lenses”, which are shaped charges that control the geometry of the shockwave passing through them.

It took several months to refine the design of the implosion mechanism. The ultimate design used both fast and slow explosives, wrapped in a truncated icosahedron (a soccer ball), with 20 hexagonal and 12 pentagonal lenses. Each lens weighed about 80 lbs (36 kg).

The implosion also needed to be perfectly timed in order to trigger the plutonium fission reaction, and an entirely new kind of detonator had to be invented for the purpose.

Designing the casing for the plutonium reactant was also a long, laborious process. An aluminum pusher and a natural uranium tamper were designed to compress and hold the triggered plutonium core together as long as possible while reflecting neutrons back into the plutonium to trigger more fission reactions.

Metallurgists also had to figure out how to properly cast the plutonium into a tight, even sphere. Plutonium is brittle at room temperature, but after some trial and error, it was found that it was malleable between 573 to 842 degrees Fahrenheit (300 to 450 degrees Celsius). 

In order to stabilize the plutonium, it was alloyed with gallium, heated, and pressed into a spherical shape. It was then coated in nickel to help prevent corrosion.

The first plutonium sphere was produced and delivered to the lab on July 2, 1945, with another delivered about three weeks later.

The Trinity Test: July 16, 1945

By the middle of July 1945, the time had come to finally test the results of years of intense research and effort.

On July 16, a device nicknamed “gadget” was placed on top of a 100-foot-tall (30.48) steel tower in the bombing range of the Alamogordo Army Airfield. It was placed on a tower to simulate it being dropped from a bomber, since an air detonation maximized the direct damage done to the target and reduced the amount of fallout generated by the blast.

The test, codenamed Trinity, was approved by the Army on the condition that the bomb was placed in a container, named Jumbo, to recover any active material in the event of a failure. They needn’t have bothered.

At 5:29:45 AM local time on July 16, 1945, “gadget” exploded with the force of 20 kilotons of TNT, producing a mushroom cloud more than seven miles tall and a shockwave felt over 100 miles away (160 km). It left behind a 250-foot (76 m) wide crater of radioactive glass, known now as trinitite, and the sound of the detonation was heard as far away as Texas.

Famously, Oppenheimer — who was on-site to observe the test — recalled thinking of the lines from the  Hindu scriptures, the Bhagavad Gita  (XI,12) : “If the radiance of a thousand suns were to burst at once into the sky, that would be like the splendor of the mighty one…”

He later recounted : 

We knew the world would not be the same. A few people laughed, a few people cried. Most people were silent. I remembered the line from the Hindu scripture, the  Bhagavad Gita ;  Vishnu  is trying to persuade the  Prince  that he should do his duty and, to impress him, takes on  his multi-armed form  and says, “Now I am become Death, the destroyer of worlds.” I suppose we all thought that, one way or another.

Legacy of the Manhattan Project

Less than a month later, on August 6, 1945, Little Boy became the first nuclear weapon ever used in combat. The gun-type bomb, packed with all the uranium-235 the Manhattan Project could produce up until that point, was dropped on the Japanese city of Hiroshima.

Between the initial blast and the resulting burn and radiation injuries suffered by those not immediately killed by the explosion, an estimated 90,000 to 146,000 people died, many of whom were civilians.

Three days later, Fat Man, an implosion-type bomb packed with the Manhattan Project’s remaining plutonium, exploded over Nagasaki, killing between 39,000 and 80,000; again, mostly civilians.

Japan surrendered less than a week later, and World War II came to an abrupt, horrifying end. 

Among those who worked on the Manhattan Project, several went on to become prominent anti-proliferation activists, like Joseph Rotblat . Others, like von Neumann, continued to advance the development of nuclear weapons as a bulwark against the even greater horrors of another world war (as they saw it).

Regardless of where one stands, there is no denying the significance of the Manhattan Project in human history, but its legacy is still unknowable. We still live under the shadow of the mushroom cloud, and its legacy can only be written by those who manage to one day escape its reach.

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March 2, 2022

The Manhattan Project Shows Scientists’ Moral and Ethical Responsibilities

As more of physics research is funded by the military, it is important to learn the full history of our past

By George Iskander

Enrico Fermi consults with a colleague during a meeting at Los Alamos during the Manhattan Project. J. Robert Oppenheimer, director of the Project, and Richard Feynman, sit behind him.

Corbis via Getty Images

After the first-ever explosion of an atomic bomb on July 16, 1945 near Socorro, N.M., J. Robert Oppenheimer, director of the Los Alamos Laboratory, recited a line from the Bhagavad Gita : “Now I am become death, the destroyer of worlds.”

Less than a month later, a quarter of a million lives were lost to the technology created by the Manhattan Project: people vaporized, buildings torn to dust, survivors dying in agony weeks or months later. There’s the lesser-known fact that about 50,000 Koreans, prisoners of Imperial Japan, died in the attacks .

The human toll is hard to comprehend. To many Americans, the bombings were justified, a necessity for ending the war. As a physicist, I have to wonder: how could my predecessors have participated in something used for such violent ends? Did no one think about walking away?

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To answer that, it’s important to understand Oppenheimer and his colleagues. Oppenheimer has captivated the American imagination as the brilliant physicist who wrestled with the implications of his creation; in the same week that he helped top brass optimize the explosion of the bomb, he was heard muttering “ those poor little people ” on his morning walk. After the war, Oppenheimer sat with President Truman to talk about international control of nuclear weapons, telling him: “I feel I have blood on my hands.”

Oppenheimer would become an advocate for nuclear peace and oppose the construction of the hydrogen bomb, but not without consequence. He was publicly humiliated in a security hearing where a colleague testified against him and his security clearance was revoked.

History has rehabilitated Oppenheimer as a tragic moral actor, with director Christopher Nolan of Inception and Interstellar fame recently announcing the production of an Oppenheimer biopic. What astonishes me, however, is the obscurity into which Oppenheimer’s colleague Joseph Rotblat has been cast. A Polish physicist, Rotblat worked with the British Mission to the Manhattan Project. Despite his reservations, he believed that stopping Nazi Germany justified the work. In March 1944, however, he had dinner with General Leslie Groves, Jr., director of the project, who remarked that its objective was to subdue the Soviet Union. Disgusted, Rotblat departed the project a few months later and would spend his life working toward atomic nonproliferation. For this, Rotblat shared the 1995 Nobel Peace Prize.

“Science became identified with death and destruction,” Rotblat said in his Nobel lecture as he described the inception of the atomic age. The comparison with Oppenheimer’s famous line is stark: two men who both knew the danger of their work yet chose different paths . The world recognized Rotblat’s impact, but I find few people, physicists or not, have heard his name.

Why does this matter? Anybody who bothers to do the research can see for themselves whether using atom bombs were necessary for ending the war: intercepted Japanese wires indicated they were preparing to surrender; American intelligence showed that the Germans were not close to developing a nuclear bomb ; Truman’s Secretary of State admitted wanting to end the war with Japan before Stalin became involved. Many project scientists favored only a demonstrative use, such as an explosion over the Pacific, which would terrify without harming. But how many Americans, whose view of history is crafted by popular narratives to support U.S. policy decisions, know all this?

How we tell history changes how it is understood. The national project predicates itself on maintaining a specific, widely disseminated version of history. In turn, it shapes our understanding of ourselves. Our decisions of who to look up to and who to talk about have consequences for the way we place ourselves relative to our predecessors and contemporaries—and the decisions that we, in turn, make. 

It means a lot if we don’t talk about Rotblat and instead center Oppenheimer. Oppenheimer’s voice, early on, would have made an impact, Rotblat believed. Instead, Oppenheimer tried to live with the bomb. Conversely, Rotblat simply ended his work with the Manhattan Project once he realized what its true purpose was. If our research leads to technology that shapes international affairs, then its politics are commensurate with the science. Rotblat spoke to this point in his Nobel lecture by quoting Lord Zuckerman, another advocate for nuclear nonproliferation: “When it comes to nuclear weapons … [i]t is he, the technician, not the commander in the field, who is at the heart of the arms race.” 

The Manhattan Project demonstrates that physicists must wrestle with the tight bonds of our research with national security. As civilian funding in science shrinks, the incentive to pursue support from the military grows. In fiscal year 2021, the National Science Foundation received $8.5 billion in total—half the $17 billion that the Department of Defense (DoD) received just for science and technology research . The DoD often funds basic research, with the hope that someday it could be useful for the military. Improvements in atomic clocks, which undergird GPS, can improve navigation for weapons and targeting, for example. Understanding turbulence can help the Air Force improve aircraft efficiency. Plasma physics helps to build new, long-range weapons. Such connections muddy the waters. I think if most physicists were asked to build a weapon, they would object. But if the military meets you on your own terms, offering to fund your basic research, the decision is difficult. 

It is even more challenging for students. The DoD maintains the National Defense Science and Engineering Graduate (NDSEG) Fellowship, which has awarded over 4,000 fellowships. In the application, the DoD details the needs of different branches of the military and asks students to connect their skills with a particular military interest . With many benefits in tow, the NDSEG is considered one of the most prestigious graduate fellowships. The DoD also offers the SMART Scholarship, a full-ride scholarship open to undergraduate and graduate students, conditional on postgraduation employment with the DoD . As tuition soars and as the cost of living for graduate students rises, these morally complex career decisions are increasingly being made for, rather than by, young Americans.

Still, we must speak and act in accordance with our conscience. We must push science to advocate for peace. We can learn from Rotblat. He didn’t make the decision to leave the Manhattan Project lightly, not to mention that the United States presented him with a false dossier alleging that he left to leak information to the Soviets. The decisions we make today are not so grand or liable to run us in as much trouble. If we turn down a grant or seek alternative research funding, who will bat an eye?

Collective action has power, but it starts with the individual. Today, we resign ourselves to the state we find the world in. We tell ourselves that we mustwork within a world dominated by the military-industrial complex, rationalizing that this is how it is. What is stopping us from doing what we believe to be right? We can’t rest easy knowing, “This is wrong,” but doing nothing. Thoughts without commensurate action effect no material change. We must have the courage to reimagine history and our place in it. In doing so, we don’t have to feel resigned. We don’t have to see our place in the world as destroyers, but instead, as creators of a better one.

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The Manhattan Project

Engineers, because much of the early research was done in New York City (Badash 238). Sparked by refugee physicists in the United States , the program was slowly organized after nuclear fission was discovered by German scientists in 1938, and many US scientists expressed the fear that Hitler would attempt to build a fission bomb. Frustrated with the idea that Germany might produce an atomic bomb first, Leo Szilard and other scientists asked Albert Einstein, a famous scientist during that time, to use his influence and write a letter to president FDR, pleading for support to further research the power of nuclear fission (Badash 237).

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Manhattan building gets $75m loan to fund 'largest conversion project in nyc history'.

The loan will help transition to the office into a larger multifamily space.

A Manhattan property has acquired a $75 million mortgage loan, which will help transition the building from an office into a much bigger multifamily space.

The current nine-story building is under the ownership of a joint venture, consisting of affiliates of both Metro Loft Management, headed by Nathan Berman, and David Werner Real Estate Investments. The property, at 219 East 42nd Street, was also the former headquarters of pharmaceutical giant, Pfizer.

The senior mortgage acquisition predevelopment loan was provided by Northwind Group. According to the private equity-based firm, the "property will be part of the largest conversion project in NYC history."

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Northwind Group Provides a $75M First-Mortgage Acquisition Loan for the 219 East 42nd Street Office to Residential Conversion Project in Midtown Manhattan

Northwind Group , a Manhattan-based real estate private equity firm and debt fund manager, announced it provided a $75 million senior mortgage acquisition predevelopment loan secured by 219 East 42nd Street , the former Pfizer headquarters in Midtown, Manhattan.

The property was acquired by a joint venture between affiliates of Nathan Berman’s Metro Loft Management and David Werner Real Estate Investments (DWREI). Combined with the conversion of the adjacent vacant property at 235 East 42nd Street (also controlled by Metro Loft and DWREI), the property will be part of the largest conversion project in NYC history.

This is Northwind’s second loan to DWREI in the last month, with the announcement coming shortly on the heels of the closing of a $95 million acquisition loan for 100 Wall Street, a 515K SF office building in Manhattan’s Financial District which was acquired by a joint venture between BLDG and DWREI. Northwind was represented by John Vavas of Polsinelli Law Firm.

The successful closing of 219 East 42nd Street underscores Northwind’s commitment to cultivating strong relationships and doing repeat business with high quality borrowers. Since the beginning of 2024, Northwind has successfully closed on ~$800 million in loans in NYC and other major gateway cities and continues to provide capital to properties that meet its investment criteria. This loan reinforces Northwind’s investment thesis, that NYC’s housing shortage provides attractive investment opportunities for lenders and developers committed to bringing more rental units to the market.

David Werner, President of David Werner Real Estate Investments, said “It was a pleasure once again closing a loan with Ran Eliasaf and Michael Ainbinder of Northwind Group. They are an accurate and efficient lender, while providing flexibility where needed and the surety of execution. Their proactive involvement and professional coordination were instrumental in achieving our objectives. I am deeply appreciative of the entire Northwind team, and I look forward to working with them again in the near future. DWREI is honored to own this asset and work on this project together with Metro Loft.”

Nathan Berman, CEO of Metro Loft, said “We’re pleased to be working with Northwind as we embark with David Werner, an industry leader, on what we are confident will be another successful conversion of antiquated office space into modern residences.”

“We are pleased to provide this financing to David Werner and Nathan Berman. This office building, located in the heart of Midtown East, is fully vacated and primed for an as-of-right conversion, which will be part of the largest office to residential conversion in NYC history. The attractive basis and top-tier sponsorship with deep experience and a clear executable business plan fit well within our debt fund’s investment thesis,” said Ran Eliasaf, Founder and Managing Partner of Northwind Group.

Northwind Group, founded in 2008 by Ran Eliasaf, is a Manhattan based real estate private equity firm that invests primarily in debt instruments through its discretionary closed-ended debt funds.

David Werner is a NYC based real estate investor who has been actively involved in commercial real estate for more than 40-years. He has extensive experience with both office and residential properties and has owned many iconic office buildings in NYC.

Metro Loft is a vertically integrated real estate development and management company founded in 1997 by Nathan Berman, who serves as the managing principal. The company has played a significant role in the residential development of Lower Manhattan, specializing in the acquisition, development, and management of prominent condominium and rental buildings, with a focus on office-to-residential conversions throughout NYC.

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Manhattan Associates Q2: Balancing Record Growth With Valuation Pressures

• Manhattan Associates, Inc. beat Q2 2024 earnings expectations with Non-GAAP EPS of $1.18 and revenue of $265.3 million.
• Strong growth in cloud and service revenue drove the company's financial results, with adjusted EPS up 34% and cloud revenue up 35%.
• Despite record-breaking results, high valuation, potential market risks, and challenges ahead suggest caution for investors.

Thomas Barwick

Manhattan Associates, Inc. ( MANH ) released its Q2 2024 earnings report late last month. The company managed to beat expectations with its Non-GAAP EPS of $1.18 and revenue of $265.3 million, topping projections by $8.94 million. The strong earnings are a result of the company’s growth in its cloud and service revenue; however, in this analysis, I argue that the company’s high valuation and the potential risks from market changes could spell worries about investors. The big earnings are great, but tomorrow’s challenges could be lurking.

Introduction

Back on July 26, 2023 , I zoomed into Manhattan Associates Inc. to look at the Q2 performance for 2023 . They came in with a robust performance which surpassed expectations by $14.4 million, however I put a caution sign on the shares as I noted the outstretched P/E ratio, and an overvalued stock. I also reminded readers of the inherent risks embedded in the fact that their bet leaned on high exposure to cloud business, a large talent acquisition drive, and a spate of early AI projects.

To understand why I leaned towards a “ Hold ” rating, it helps to know what each of my call ratings means. A “ Sell ” rating tells investors to either cut their losses (or take their profit) and find something else, while new investors should avoid it altogether. A “ Buy ” call suggests new investors consider jumping in, and existing shareholders should think about adding more. Finally, my “Hold” rating is for those already in the game to stay put, expecting the stock to move with the market, but it also tells new investors to look for better entry points (or alternatives).

Seeking Alpha

When I called “Hold” on MANH, they lagged the market until Q4 2023. But then their Q4 earnings and revenue beat, which they've been doing every quarter since (see above), set them up for a solid run (post my “hold” call), outperforming the S&P 500 36% to 22.56%.

Grassroots Trading MANH Rating Performance (Seeking Alpha)

Today, I'm shifting focus to Manhattan Associates' Q2 2024 earnings report, and I’m going to see how they performed and whether holding is still the smart play or if it's time to rethink the strategy.

Record-Breaking Q2 2024 Results: Cloud Solutions Driving Growth

Manhattan Associates, Inc. is a top player in global tech and since 1990, this Atlanta-based company has been creating software that helps businesses keep their supply chains, inventory, and omnichannel operations on point. They roll out a range of tools, like Warehouse Management Systems (“WMS”) and Transportation Management Systems (“TMS”). Their Manhattan Active Platform is cloud-based and serves industries like retail, logistics, and healthcare, reaching across the Americas, Europe, and Asia.

A brief look at their latest Q2 2024 results and Manhattan Associates beat the street again with record revenue and earnings. Total revenue grew 15% to $265 million, with demand across the board.

Adjusted EPS rose 34% to $1.18, beating market expectations. Cloud again pulls its weight, with revenue up 35% to $82 million, proving that their cloud solutions are catching on fast.

Looking at Seeking Alpha’s growth metrics , YoY revenue is up 17.49%, way above the sector's 3.47% average. Moreover, their forward growth projection looks good at 14.66%. EBITDA growth is even better with YoY growth at 31.91% and a forward growth of 19.46%.

Note: More color on the “C” grade below in “Risks & Headwinds”

EBIT and EPS growth are also impressive: YoY EBIT is up 33.00%, and EPS is up 42.01%, which demonstrates that MANH is growing profits and shareholder value at an accelerating pace, which is precisely what their stock needs.

Meanwhile, returning to their cloud solutions, Manhattan Associates is set to release new software – Manhattan Active Supply Chain Planning – this fall, the culmination of a decade-long effort to move their apps to the cloud. Their competitive move makes them “cloud-first” in the industry.

What that means is that the software is innovative because it is the first to consolidate Supply Chain Planning and Execution into one cloud solution, and customers will soon run everything—demand planning, inventory, labor, transportation—all on one platform. The key to the whole thing is that you can see your need for long-term transportation and short-term labor both in the same place. This is a huge selling proposition, as it helps companies plan smarter, save money, and get faster at responding to change—all in real-time optimization, which management believes is the next wave in cloud technology evolution and represents a game-changer in the industry.

Back to Q2, cloud growth and services revenue both took off. Services revenue jumped 10% to $137 million, helping to further boost the company’s financial results.

CEO Eddie Capel, noticing the services revenue performance, sounded upbeat and said:

While the global macro environment certainly remains volatile, Manhattan’s business is solid, and we’re very optimistic about our business opportunity. Demand for our solutions are robust, customer satisfaction is high and investment in R&D and our associates continue to widen our technological leadership across our supply chain planning, execution and omni-channel retail offerings.

Manhattan Associates saw a 29% jump in its Remaining Performance Obligation or RPO – which is its leading indicator of growth – hitting over $1.6 billion. CFO Dennis Story noted that the FX impact on RPO or revenue in the quarter wasn’t material. Looking ahead, he’s feeling comfortable that the company will hit its bookings goals with a record pipeline in the back half of 2024 and also reaffirmed their 2024 RPO target, aiming for a midpoint of $1.78 billion.

Adjusted operating profit also climbed 36% to $93 million, pushing the adjusted operating margin to 35%, up 540 basis points from last year.

Free cash flow was strong. Operating cash flow jumped 81% to $73 million, with a 27% free cash flow margin. Manhattan Associates keeps pushing innovation, investing in new tech like AI-powered products Manhattan Active Maven and Manhattan Assist, and soon, the aforementioned Manhattan Active Supply Chain Planning. The balance sheet looks solid, too, with $203 million in cash and zero debt by the end of the quarter.

The company repurchased another $75 million of shares in Q2, bringing the year-to-date total to $148 million. And lastly, confident about the future, Manhattan Associates raised its 2024 revenue guidance to $1.036 billion to $1.044 billion, aiming for 17% growth without license and maintenance revenue.

At the time of my analysis, MANH was trading at $257.35 and a P/E ratio of 63.12x, I still believe that it's way overvalued compared to its history and the broader market. With the fair value ratio pointing to a much lower 15.00x, it's evident that investors really love this company, but I believe the market might be too hyped about the company’s growth.

Fast Graphs

An 11.82% earnings growth rate is definitely solid, but it doesn’t back up that high P/E multiple; normally, a P/E of 43.67x would make more sense for a company like this, but we’re not seeing normal here: the gap between fair value and the current price means investors might be betting too much on the company nailing its growth strategy, without considering the risks.

Seeking Alpha’s valuation metrics align with my perspective, giving the stock an overall “F” rating.

On the bright side, the company’s balance sheet looks strong, with that low debt ratio of 17.44% I mentioned earlier; but with a TEV of $15.82 billion, the market’s placing a big bet on Manhattan Associates and if growth slows down or there’s a market correction, that could spell trouble.

Risks & Headwinds

Strong showing from Manhattan Associates, but lingering challenges. The general global economic nervousness could also influence performance going forward. Pointing to the quarterly ups and downs, the company noted that several large deals slipped. That’s why executives cut their forecast for services revenue by $4 million, largely due to “project delays and deal closings.” The company also expects maintenance revenue to hit the low-end of the forecasted range, coming in at $134 million for the year, a drop of 7%.

Turning back to Seeking Alpha's Growth metrics, the Levered Free Cash Flow (FCF) is up, but barely above the sector average at 25.59%. MANH isn't turning growth into cash as well as they could.

If they hit any snags, cash flow could become a problem. Operating cash flow and free cash flow per share growth are solid, but they don't pop like the revenue and earnings numbers. Forward operating cash flow growth sits at 22.23%.

It’s good, but not on par with their other metrics. This suggests they’re making money, but it’s not all turning into usable cash. Tangible book value and total assets are growing fast, showing MANH is heavily investing; tangible book value jumped 64.70% year-over-year, and this big spending explains why free cash flow growth is slower.

Finally, the shift from license and maintenance revenue to cloud revenue might squeeze margins, with a 120-basis-point hit. Big deals could cause unpredictable bookings, leading to revenue swings. The company expects a higher tax rate, around 21.5% for Q3 and Q4, which might dent net income. Adjusted EPS looks solid, but GAAP EPS is forecasted lower at $3.12 for the year and $0.74 for Q3. All these factors could affect Manhattan Associates’ future financials, despite a strong recent quarter.

I’m staying with a “Hold” on Manhattan Associates. The company is firing on all cylinders, especially in the cloud, but the shares are still looking rich. If you already own this one, hang tight. Those who don’t own it should sit on the sidelines until it gets cheaper because there’s plenty of risk here.

This article was written by

Analyst’s Disclosure: I/we have a beneficial long position in the shares of MANH either through stock ownership, options, or other derivatives. I wrote this article myself, and it expresses my own opinions. I am not receiving compensation for it (other than from Seeking Alpha). I have no business relationship with any company whose stock is mentioned in this article.

Seeking Alpha's Disclosure: Past performance is no guarantee of future results. No recommendation or advice is being given as to whether any investment is suitable for a particular investor. Any views or opinions expressed above may not reflect those of Seeking Alpha as a whole. Seeking Alpha is not a licensed securities dealer, broker or US investment adviser or investment bank. Our analysts are third party authors that include both professional investors and individual investors who may not be licensed or certified by any institute or regulatory body.

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Northwind Group Lends $75M on Office-to-Resi Conversion of Former Pfizer HQ 

By andrew coen august 21, 2024 4:47 pm.

A joint venture between Nathan Berman ’s Metro Loft Management and David Werner Real Estate Investments has secured $75 million of acquisition financing to develop New York City’s largest office-to-residential conversion project at the former Pfizer headquarters building in Midtown Manhattan, Commercial Observer can first report.

Northwind Group provided the senior acquisition predevelopment loan on the sponsorship’s 219 East 42nd Street property, which was formerly the global headquarters of Pfizer before the pharmaceutical giant relocated to Tishman Speyer ’s Spiral office tower at Hudson Yards in late 2022. 

Metro Loft and Werner are also planning to convert the adjacent office property at 235 East 42nd Street into residential housing for 1,500 combined rental units, which would surpass Metro Loft’s 1,300 units planned at 25 Water Street in Lower Manhattan, The Real Deal reported in March. 

“This office building, located in the heart of Midtown East, is fully vacated and primed for an as-of-right conversion, which will be part of the largest office to residential conversion in NYC history,” Ran Eliasaf , founder and managing partner of Northwind Group, said in a statement. “The attractive basis and top-tier sponsorship with deep experience and a clear executable business plan fit well within our debt fund’s investment thesis.”

IPA Capital Markets ’ Max Herzog arranged the financing.

The conversion of the nine-story 219 East 42nd property will involve developing a 29-story residential tower with up to 660 apartments, according to Northwind. 

Werner acquired interests in both 219 East 42nd and 235 East 42nd in 2018 for $355 million from Alexandria Real Estate Equities with Berman inking a contract early this year for a minority 50 percent stake, according to TRD . The purchase price details from the Metro Loft deal were not immediately available. 

Berman said in a statement called Werner an “industry leader” and he is confident the project “will be another successful conversion of antiquated office space into modern residences.”

Werner said in a statement that the firm is “honored to own this asset and work on this project together with Metroloft.”  

Andrew Coen can be reached at [email protected]  

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