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Part One: Beginnings of the Atomic Mission

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Chapter 1: The Army and the Atomic Energy Program, 1939–1942

At eight o’clock on the evening of 17 June 1942, Col. James C. Marshall received a teletype message from Washington, D.C., to report to Maj. Gen. Eugene Reybold, chief of the Corps of Engineers, “for temporary duty,”1 thus interrupting his present assignment as commanding officer of the Syracuse (New York) District. Arriving at General Reybold’s office the next day, Marshall received further instructions to report to Brig. Gen. Wilhelm D. Styer, chief of staff to the commanding general of the War Department’s Services of Supply, a major division newly created to oversee Army logistics. Late in the afternoon, Colonel Marshall learned from General Styer the precise nature of his new assignment: General Reybold had chosen him to form a new engineer district “for construction of a new manufacturing plant.”2 The location had not been selected but, Styer explained, the plant would be part of a project already in progress to develop atomic energy for military purposes. Thus the Army became directly involved in a project in which it had been playing a minor and somewhat intermittent role since the fall of 1939.

Origins of the Army’s Role

The Army’s expanded role in the American atomic energy program in mid-1942 grew out of developments that had occurred as a result of the outbreak of World War II and the subsequent involvement of the United States in that conflict. On the morning of 12 October 1939, persuaded by Alexander Sachs’s urgent arguments, President Roosevelt agreed to investigate the desirability of providing some preliminary support for independent and private research. Roosevelt’s military aide, Maj. Gen. Edwin M. Watson, immediately requested that the Army and the Navy send officers to the White House to talk to an “inventor” about a new explosive. At two o’clock that same afternoon, the Army sent Lt. Col.

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Keith F. Adamson, chief of the Ammunition Division, Ordnance Department, and his chief civilian assistant, Arthur Adelman; the Navy sent Comdr. Gilbert C. Hoover, also an ordnance specialist. In General Watson’s office, Sachs repeated much of his earlier presentation to the President. After some discussion, the group broke up with the understanding that Watson would advise them what specific action the President desired.3

The Army’s Chemical Warfare Service (CWS) also received Sachs’s material on atomic energy. Lt. Col. Haig Shekerjian, the CWS executive officer, and another chemical warfare officer may have been present at the meeting in the White House, or they may have been briefed later in the afternoon. General Watson’s objective was to test Sachs’s information against the knowledge and experience of the technical services most likely to be concerned with development of nuclear research and bombs. Ironically, the technical service that eventually had the most to do with development of the atomic bomb, the Corps of Engineers, was not consulted.4

The first reaction of the Army representatives to the military potentialities of atomic energy was not generally enthusiastic. Colonel Adamson displayed a cool skepticism, although he later warmed to the subject. He apparently questioned whether nuclear research had advanced far enough for the government to support it with any reasonable hope of success. Moreover, with an eye to Sachs’s Wall Street background, he was suspicious of the financier’s motives in urging purchase of Belgian Congo uranium.5

A similar response came from the Chemical Warfare Service. Despite Colonel Shekerjian’s favorable reaction, Maj. Maurice E. Barker, chief of the CWS Technical Division, expressed a decidedly negative view. After studying Einstein’s letter and Szilard’s memorandum, Major Barker concluded that there was “no basis” for believing that the bombardment of uranium by neutrons would produce an explosion. While conceding that the proposed nuclear research “would be extremely interesting, and might have considerable scientific value,” he thought that “the chance of anything of military value being developed . . so slight that it would not justify the expenditure of funds available for research for that purpose.”6

The Army’s initial skepticism may be attributed to a number of factors. For all of Alexander Sachs’s enthusiasm, even the group of American and foreign-born physicists still regarded the potentialities of atomic energy as only a “reasonable possibility,”7 as

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the tentative tone of Einstein’s letter and Szilard’s memorandum readily showed. Unlike the Navy, in 1939 the Army had no central research organization that might have seized upon the abstract possibilities of atomic energy. Consequently, budget-minded Army officers, who had served through a period of extremely restricted military expenditures in the 1930s, were not likely to lose their restraint over new and possibly far-fetched ideas. They had witnessed drastic cuts in funds, especially for Army research and development, which was allotted only 1.1 percent of military expenditures in fiscal year 1939. Army policy called for immediate development of critical items rather than eventual production of better weapons and equipment through prolonged research. Ordnance and chemical officers were, of course, particularly aware of this situation. Thus, it was hardly surprising that Sachs’s proposals failed to translate their scientific conservatism into military enthusiasm.8 Not until civilian research and development had buttressed the theoretical predictions of the physicists with undisputable scientific evidence and the nation was involved in war would the Army assume a principal role in developing the military potentialities of atomic energy.

Decision To Develop Atomic Weapons

Through the President’s Advisory Committee on Uranium, established on 12 October 1939, the Army had an opportunity to express its generally negative reaction to the military potentialities of atomic energy. This small group, charged with making recommendations on the ideas and materials submitted by Sachs, was comprised of Colonel Adamson, Commander Hoover, and, as chairman, Lyman J. Briggs. Briggs was director of the National Bureau of Standards, which was one of the principal government agencies of the pre-World War II period concerned with research in the physical sciences.9

The first meeting of the Uranium Committee, as it came to be called, took place on the morning of 21 October at the Bureau of Standards. The committee had invited Alexander Sachs and, at his suggestion, also Leo Szilard, Edward Teller, Eugene Wigner, and Albert Einstein to attend its session. Einstein was unable to be present but two other physicists, Fred L. Mohler of the Bureau of Standards and Richard B. Roberts of the Carnegie Institution, attended to provide the committee with technical guidance. Szilard, Teller, and Wigner outlined the steps they believed necessary to attain a chain reaction in the uranium-graphite system proposed by Fermi and Szilard. During their presentation,

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the three scientists requested $6,000 to purchase the graphite and emphasized the need for secrecy about all activities relating to nuclear research.

In the discussion that followed, three schools of thought became apparent. Colonel Adamson and Commander Hoover, generally skeptical, stated their belief that several years of further research would be needed even to determine whether the military possibilities of atomic energy were sufficient to justify government support. In contrast, Sachs, Briggs, and Teller were almost enthusiastic about the chances of success. Maintaining a more conservative approach, Szilard and Wigner portrayed the great possibilities of their work but also stressed the as yet tentative nature of their conclusions.10

In spite of the cautious attitude of Adamson and Hoover, the Uranium Committee’s report to the White House on 1 November gave the scientists in effect what they wanted. While conceding that the harnessing of atomic energy for power or bombs was still only a theoretical possibility, the committee nevertheless recommended that “in view of the fundamental importance” and “potential military value” of nuclear research, “adequate support for a thorough investigation of the subject should be provided.” This support should include funds for immediate purchase of 4 metric tons of pure graphite and, if the results of initial experiments warranted continuing the program, additional funds to obtain 50 tons of uranium oxide.11

The Uranium Committee submitted its report and recommendations to President Roosevelt through General Watson. Apparently viewing the report as preliminary, Watson asked Chairman Briggs for a special recommendation before he advised the President. Until then, no executive action could be expected.

Consequently, the members of the Uranium Committee kept in touch with the nuclear research program at Columbia University, awaiting word of progress from the scientists. In the interim, the Naval Research Laboratory continued its interest in university research that pertained to its own investigations into isotopic separation. At this stage, however, neither the Navy nor the Uranium Committee made any effort to coordinate or link the various nuclear research programs in progress. Such attempts as were made came from the scientific community and from Sachs rather than from any governmental agency.12

Then, in January 1940, Briggs took the first concrete step to obtain government funds for the university scientists. From the Navy, up to now more interested in nuclear research than the Army, Briggs obtained a

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promise of $3,000. On 15 January, he called on Maj. Gen. Charles M. Wesson, the chief of Army Ordnance, and asked him to match this sum. Briggs outlined the potentialities of atomic fission. “It appears,” reads the account of the conversation in General Wesson’s office diary, “that this development has possibilities from an explosive viewpoint.” These “possibilities” and Briggs’s reference to the fact that the President was “interested in this project” were enough to make the Ordnance chief agree to advance $3,000 out of Picatinny Arsenal funds for the development of explosives.13

The Army and Navy funds went to the Bureau of Standards, which allotted them to Columbia University in mid-February. Fermi and his colleagues used the money to purchase graphite in quantities that, at the time, seemed huge. They needed a sufficient amount of the highly purified carbon substance to determine its capture cross section, that is, its capacity to absorb neutrons. With this information they could then ascertain the practicability of achieving a slow-neutron chain reaction in a uranium-graphite system.14

Meanwhile, Alexander Sachs and the scientists exerted increasing pressure on the President and the Army and Navy. Einstein wrote to Sachs on 7 March, summarizing the situation and suggesting that the information concerning new evidence of German interest in atomic energy be passed on to President Roosevelt. This Sachs did, including also Einstein’s recommendations that steps be taken to halt publication of articles on atomic subjects and that a “general policy ... [be] adopted by the Administration with respect to uranium.” But Einstein’s views brought no immediate response from the White House. In fact, after discussion with Colonel Adamson and Commander Hoover in late March, General Watson accepted Adamson’s suggestion that no further action be taken until an official report on the research at Columbia was available.15

The official report was not ready, however, when the Uranium Committee held its second meeting on 27 April 1940. The meeting took place as a result of several factors, including Sachs’s continued urgings for greater support, the reports of promising progress in the nuclear experiments at Columbia and elsewhere, and an ominous turn of events in the war of Europe. Since the first meeting in October 1939, the atomic scientists had proven definitely that fission occurred only in the U-235 isotope and, in experiments with the centrifuge system of isotopic separation at the University of Virginia, had been successful in enriching a gram of uranium to 10 percent U-235. In Europe, the Germans had successfully invaded Norway in early April and, as a result, secured control of the Norsk Hydro plant, the only large facility in the world producing heavy water. Thus

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they had obtained a ready source of the substance they were suspected of using as a moderator to achieve a slow-neutron chain reaction.

Chairman Briggs, Colonel Adamson, and Commander Hoover now listened more sympathetically to the arguments presented by Alexander Sachs, Enrico Fermi, George Pegram, Leo Szilard, Eugene Wigner, and Rear Adm. Harold G. Bowen, director of the Naval Research Laboratory. While the committee still did not make any formal recommendations, it reached general agreement that nuclear research should be vigorously pursued, even if this required large sums of money, and that steps should be taken, as Szilard strongly urged, to halt further publications on atomic matters.16

Developments in May 1940 in the laboratory and on the war front brought further justification for providing additional funds for nuclear research. Promising results at Columbia led scientists there to propose a plan to study methods of uranium isotope separation, hopefully with Navy support, and to establish a large-scale experimental program that would demonstrate beyond any doubt that a chain reaction could be maintained in a uranium-graphite system. The Germans’ successful invasion of Belgium and Holland in mid-May and new reports on their interest in uranium research underlined Sachs’s efforts to secure action on control of Belgian uranium and to obtain financial and administrative support for atomic research in the United States.17

New funds came from a variety of sources. On 23 May, the Carnegie Institution of Washington allotted $30,000 for research on uranium by members of its own staff. A short time later, Colonel Adamson furnished $20,000 from Army Ordnance funds to combine with a substantially larger contribution from the Navy and some money from the Bureau of Standards, making a total of more than $100,000. This amount was more than sufficient to underwrite contracts at Columbia and the University of Virginia and to increase support of the work at the Naval Research Laboratory.18

German occupation of Belgium gave urgency to the question of how the United States could control and acquire the rich uranium ore in the Congo. Seeking a solution, Alexander Sachs met with President Roosevelt at the end of May and, a few days later, also with Uranium Committee Chairman Briggs, Professor Harold C. Urey, a chemist on the staff at Columbia University, and Admiral Bowen of the Naval Research Laboratory. At

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Briggs’s suggestion, Sachs began looking into the possibility of getting uranium directly from the Congo.

For some time Sachs had been aware that Edgar Sengier was in New York. Managing director of Union Miniere du Haut Katanga, the Belgian firm that controlled the Shinkolobwe mine in Katanga Province of the Congo, Sengier had come to New York from Brussels in the fall of 1939, aware of the rising importance of uranium from conversations with French and British scientists. He had ordered shipped to America all radium held by his firm in Belgium – some 120 grams worth nearly $2 million. At the same time, he had directed that uranium ores stocked by Union Miniere at Oolen, Belgium, also be shipped to the United States, but little or none was sent before the German invasion made it impossible.

Sachs and Urey went to see Sengier in New York in early June 1940. Sengier gave them considerable information on the status of Congo uranium but would not agree to Sachs’s proposal that Union Miniere ship ore to the United States, even with the stipulation that U.S. officials would not re-export the ore without special permission.19

Failure to achieve an agreement with Sengier left the uranium research program dependent upon Canadian sources. Fortunately, by the end of 1940, small amounts of Canadian uranium were available as a result of arrangements based on earlier conversations between Dean George B. Pegram of Columbia University and a representative of Eldorado Gold Mines, Ltd., owner of the Canadian deposits.20

Funds contributed in the summer of 1940 began a two-year period of rapid growth in the program to exploit atomic energy for military purposes. During this time, American governmental leaders left development of the new energy source to civilian organizations, in spite of its obvious application to military objectives and its close relationship to the expanding conflict in Europe and Asia. Army participation ceased almost completely, and the Navy continued only a relatively small isotope separation project. Under civilian guidance, the work on atomic energy became a major component in the federal government’s greatly broadened program to apply the achievements of American science to the requirements of modern warfare. Thus, by early 1942, when the Army renewed its participation in the development of atomic energy, the program had evolved into a large research and development enterprise, with civilian scientists carrying on

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program activities at a number of sites across the country.

Establishment of the NDRC and OSRD

The organizational framework of the American atomic energy program first began to take shape in the summer of 1940. In June, a number of the scientific leaders took the initiative in providing a more effective administrative organization. At Leo Szilard’s suggestion and with the backing and approval of Admiral Bowen and Lyman Briggs, Harold Urey organized a committee of scientists to advise Briggs on atomic energy and to study the question of security. This group, the Advisory Committee on Nuclear Research, met for the first time on the thirteenth under Urey’s chairmanship. One of its first actions was to formulate, with support of American scientific journals, a policy on secrecy that eventually halted publication of scientific papers on atomic energy in the United States. Thus, a beginning was made in solving what was to become another major and persistent problem – how to maintain a level of secrecy hitherto never attempted in so large and diverse a project.21

Even as the Advisory Committee on Nuclear Research was meeting, events were taking place that would increase effective leadership and direction for the entire American scientific war effort, including the atomic energy program. Since the invasion of Belgium, Sachs had been urging Roosevelt to establish a “Scientific Council of National Defense” to administer “the testing and execution of technical projects of utility for national defense.” Another strong advocate for such a council was Vannevar Bush, president of the Carnegie Institution of Washington since 1939.22 For some time he had discussed his ideas with several of the nation’s foremost scientists and had gained their support for the project. In addition, the country’s military leaders, including both Army Chief of Staff General George C. Marshall and Chief of Naval Operations Admiral Harold R. Stark, strongly favored the proposal. Consequently on 15 June 1940, the President established the National Defense Research Committee (NDRC), with Bush as chairman, to direct, coordinate, and carry out a national program of military research and development. Membership was drawn from the National Academy of Sciences, with Brig. Gen. George V. Strong, chief of the War Plans Division, representing the Army and Rear Adm. Harold G. Bowen, director of the Naval Research Laboratory, representing the Navy.

With establishment of the NDRC, the President made provision for continuation of the atomic energy program. He asked Vannevar Bush to reconstitute the original Uranium Committee as a subcommittee of the NDRC. The new Committee on Uranium, reporting to Bush and with Briggs continuing as its chairman, included six other scientists but lacked the service representation that the

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original committee had. Briggs was authorized “to maintain close and direct contact with those officers of the Army and Navy most directly interested,” but only Ross Gunn of the Naval Research Laboratory continued to serve on the new committee.23

On 1 July, Briggs reviewed for Bush the earlier activities of the Committee on Uranium. At the same time, he requested the $140,000 that he and Urey’s Advisory Committee had agreed was necessary for purchasing uranium metal and pure graphite and for making further measurements of the fundamental nuclear constants. At its first formal meeting the next day, the NDRC considered Briggs’s request, but its members found themselves in a dilemma. The basic NDRC mission was research and development of weapons and equipment with direct application to the war. NDRC scientists still regarded the chances of an atomic weapon as “very remote,” in Bush’s words, and even the possibility of nuclear power for battleships or submarine propulsion seemed a distant eventuality at best. Given the need for funds and trained scientists in other areas, there was grave doubt as to the wisdom of allocating money and energy to “what might eventually appear to have been wild research.” Yet, there was a danger that German nuclear research might prove successful. Committee members concluded, therefore, that prudence demanded acquisition of knowledge of the fundamental physics of atomic energy. Accordingly, the NDRC approved Briggs’s request in principle and asked him for further definite proposals for “a careful, but not elaborate or expensive program.”24

Promise of NDRC funds opened the way for the future rapid expansion on atomic research in the United States. But until these new funds became available, the atomic program had to continue to draw upon money supplied earlier by the Army and the Navy. Even the $40,000 for the first NDRC contract for atomic research, an agreement signed with Columbia University in early November, came out of the remaining Army-Navy funds.

Beginning with the NDRC’s allotment on 25 October of the $140,000 requested by Briggs on 1 July, there followed a series of contracts and transfer agreements arranging for nuclear research by various institutions. By the spring of 1941, the NDRC had committed nearly $500,000 for work at Columbia, Harvard, Princeton, the University of Minnesota, the Standard Oil Development Company, Iowa State College, Cornell, the University of Chicago, Johns Hopkins, the Carnegie Institution of Washington, the University of California (Berkeley), the University of Virginia, the Bureau of Standards, and the Department of Agriculture. While the NDRC’s expenditure for atomic energy was small compared with amounts allotted to

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other wartime scientific research, it represented a significant financial boost for the American program. As Alexander Sachs observed a few years later, the program had become “invested with the importance, the resources and the secrecy available to the Government of the United States ... for the translation of the idea into a reality. …”25

While the NDRC was able to focus the energy and capabilities of civilian scientists on many aspects of military technology, it left certain gaps in the program to mobilize American science for war. Hence, at the end of June 1941, President Roosevelt established the Office of Scientific Research and Development (OSRD), with the NDRC as one of its subordinate agencies. Bush became OSRD director and James B. Conant, president of Harvard University, succeeded Bush as NDRC chairman. In this reorganization the Committee on Uranium under Briggs remained within the NDRC, but it was somewhat enlarged and was renamed the Section on Uranium. Again it included no Army or Navy representatives, and even Ross Gunn of the Naval Research Laboratory was no longer a member.26

New Advances in Atomic Research, 1940–1941

In mid-July 1941, enthusiastic over reports that atomic scientists in America and Great Britain were making significant progress in atomic research, Vannevar Bush reported to the President that “new knowledge” made “it probable that the production of a super-explosive may not be as remote a matter as previously appeared.”27 At Columbia, supported by investigations at Princeton and the Universities of Chicago and California (Berkeley), researchers produced sufficient favorable data on the capture cross sections for the neutrons of U-235 and U-238 and on the absorption qualities of graphite to justify construction in July 1941 of the first lattice pile – a large graphite cube in which containers of uranium oxide were distributed at equal intervals. The research results also convinced many more scientists that a chain reaction in a uranium-graphite system eventually would be achieved.

At Berkeley, physicists working with Ernest O. Lawrence on the bombardment of uranium with neutrons discovered that the capture of fast neutrons by U-238 transmuted that isotope first into element 93 and then into element 94, which they named neptunium and plutonium, respectively. After further investigation of these transuranium elements, neither of which was then known to exist in nature, Lawrence’s group concluded that plutonium had the same fission characteristics as U-235; it could be split by neutrons and would, in turn, release more neutrons. U-238, hitherto regarded as worthless for energy purposes, was in fact a prime source.

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Ernest O

Ernest O. Lawrence, Arthur H. Compton, Vannevar Bush, and James B. Conant (left to right), four of the Manhattan Project’s scientific leaders (1940 photograph)

Furthermore, as there was reason to believe that chemical separation of plutonium from uranium might prove more practicable than isotopic separation of U-235 from U-238, chances that an atomic bomb based on a fast-neutron chain reaction could be built were tremendously increased.

American atomic scientists learned of encouraging British developments on isotopic separation by gaseous diffusion and on heavy water as a moderator in a slow-neutron chain reaction system through a scientific information exchange program, begun in the fall of 1940. With the support of the War and Navy Departments, NDRC members conferred informally with British scientific representatives, both in the United States and in England, achieving a limited exchange of data about the progress of nuclear research in each country.28

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In the summer of 1941, a special reviewing committee of the National Academy of Sciences supported Bush’s optimism. The committee, established at Briggs’s suggestion that an impartial evaluation of the atomic program was needed, first met in May under the chairmanship of Arthur H. Compton, head of the physics department and dean of the Division of Physical Sciences at the University of Chicago. The committee’s initial report was buttressed by supporting remarks from Briggs, and on 18 July the NDRC approved contracts and transfers amounting to nearly $400,000 for chain reaction, nuclear power, and isotope separation research. While the NDRC remained cautious in its estimate of whether atomic energy could be harnessed in time to affect the outcome of the war, it recognized that continued progress in nuclear research would eventually require establishment of a long-range program so vast and expensive that in wartime only the Army or Navy could carry it out.29

The pressure of an all-out attack on the problem of atomic energy grew rapidly. At the University of California, Lawrence was more and more convinced of the feasibility of using plutonium to make an atomic bomb and he communicated his enthusiasm to both Compton and Conant. Compton was especially interested and he, in turn, talked with other nuclear researchers. From Urey and physicist John Dunning, who also was on the staff at Columbia, he learned of progress on isotope separation, and from Fermi he received encouraging news of the results of experiments with the lattice pile. Most of the scientists now involved felt that the atomic energy program should be pushed, and in mid-October, at Conant’s suggestion, Compton reconvened his reviewing committee, now somewhat enlarged, to prepare another report.30

On 3 October, Bush received the first official copy of a British review of atomic energy that had been completed in mid-July, but he was not yet at liberty to disclose its contents to the NDRC. The British scientists had optimistically concluded that a uranium bomb could be built with an explosive power of 1,800 tons of TNT. They indicated a rough idea of its critical mass and possible methods of assembly and fusing. They thought the gaseous diffusion method offered the best answer to the problem of separating a sufficient amount of U-235 and the uranium-heavy water system gave promise as a means for producing power and plutonium.31

Top Policy Group: Preparing for Army Take Over

Increasing conviction that atomic bombs were feasible prompted Bush to take immediate steps to obtain the high-level policy decisions he had foreseen would be necessary to assure aggressive pursuit of the uranium program. On 9 October 1941, almost

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two years to the day on which Alexander Sachs first informed the President about atomic energy, Bush had a long conversation with Roosevelt and Vice President Henry A. Wallace. In late July, Bush and Wallace had discussed the progress of the American program; now, supported with more concrete evidence of possible success at hand, they were considering what the President could do to further develop the program. The OSRD director outlined the current status of research in both the United States and Great Britain, pointing up the general optimism of the scientists in both countries but, at the same time, emphasizing that their predictions could not be guaranteed. He indicated, too, that much work would be required before success could be anticipated.

President Roosevelt agreed that the atomic energy program must be provided with a better organization and more funds and that arrangements should be made for a complete interchange of information with the British. He directed formation of what was informally designated the Top Policy Group, to be headed by himself – although he never actually participated in its proceedings – and to consist of Vice President Henry A. Wallace, Secretary of War Henry L. Stimson, Army Chief of Staff General George C. Marshall, Vannevar Bush, and James B. Conant.32 Thus the President took the first step in implementing a maximum effort to develop an atomic bomb as soon as possible. He also decided that the Army, and not the Navy, would be given the primary responsibility for attaining this goal.

The NDRC had concluded that no private institution or relevant government agency had the means or personnel to carry out the extraordinarily large tasks of plant construction and administering development of a nuclear weapon. The choice, then, was the Army or the Navy. When Roosevelt appointed Secretary Stimson and General Marshall to the Top Policy Group that had no naval representation, he decided in effect that the Army was to manage the job. Why had the President selected the Army when the Navy had exhibited much greater interest in nuclear research? Indications are that Bush and his associates had decided that the Army was the more appropriate choice for the project. The end product was to be a bomb, presumably delivered by an Army bomber. Also the Army, judged on the basis of its past experience and its organization, appeared better fitted to undertake the vast construction program.33

The President also had agreed to establish an effective exchange of information with the British. On 11 October he communicated with Prime Minister Winston S. Churchill, suggesting that they correspond or talk about atomic developments, inaugurating

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Secretary of War Henry L

Secretary of War Henry L. Stimson

a period of regular interchange between the two countries.34

The President’s efforts to strengthen the American atomic energy program were reinforced a few weeks later by Compton’s National Academy reviewing committee. On 6 November, the committee issued another report that, while not as optimistic as the earlier British study, nevertheless constituted a strong endorsement of an expanded atomic bomb program. Because Compton’s group had prepared its report without access to the British conclusions – Bush up to now had been bound not to disclose them – its findings consisted of both a further verification of the British views and an independent recommendation.

The committee report stated that “within a few years ... military superiority” might be determined by U-235 bombs and that building these bombs seemed “as sure as any untried prediction based upon theory and experiment can be.” The amount of U-235 needed for each bomb would be between 2 and 100 kilograms, producing an explosive energy per kilogram of U-235 equal to that of about 300 tons of TNT and a destructive effect equivalent to about 30 tons of TNT. Atomic bombs could thus be of “decisive importance” in defeating Germany and, based on an estimate that military and industrial targets in Germany could be devastated with 500,000 tons of TNT bombs, from 1 to 10 tons of U-235 would be needed to do the same job. This much U-235 could be obtained, continued the report, by one or more methods of isotope separation, of which the gaseous diffusion and centrifuge methods appeared to be furthest along in development. In accordance with instructions from Bush, the committee did not discuss plutonium and it purposely played down the expense of producing U-235 bombs to avoid arousing government fears of excessive costs. “If all possible effort is spent on the program,” the report concluded, “fission bombs” might “be available in significant quantity within three or four years.”35

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This prediction came at a time when only infinitesimal amounts of plutonium had been produced and when no appreciable quantity of U-235 had been separated from U-238, no large amounts of uranium metal or moderators produced, and, as yet, no chain reaction achieved. Nevertheless, the committee report, as had its British counterpart, reflected the substantial progress that had been made in research. Although some scientists were still no more convinced that atomic weapons were imminently possible than they had been a year earlier, the threat of American involvement in war now seemed far stronger, with the result that large expenditures of money and effort were no longer seen as extravagances but rather as necessary precautions.

Bush’s first action after receiving Compton’s committee report was to show it to Secretary of War Stimson. Whether the 6 November meeting was Stimson’s first word of his appointment to the Top Policy Group is not clear, but there is no doubt about his reaction to the awesome possibilities of an atomic bomb. “A most terrible thing,” he called it, sensing the grave responsibility falling upon those who would unleash the power of such a devastating weapon.36

During the next few weeks, Bush apparently reviewed the entire American atomic energy program and, in compliance with the President’s instructions, devised a plan for an administrative reorganization designed to expedite efforts “in every possible way.”37 Finally, on 27 November, Bush forwarded the report of Compton’s reviewing committee to Roosevelt and, presumably, his own recommendations for the new organization. The NDRC endorsed these recommendations on the twenty-eighth. Then on 6 December 1941, the day before the Japanese attack on Pearl Harbor, Conant – speaking for Bush – announced the details of the new organization to those persons who would now join together in a maximum effort to develop an atomic bomb.

Under the new organization, the atomic energy program was divorced from the NDRC and placed under the immediate supervision of Bush as the OSRD director. Bush reported directly to the President, at the same time keeping Vice President Wallace and Secretary Stimson fully informed. The scientific group under Bush was now called the OSRD S-1 Section, dropping the word uranium for security reasons. Its function was to recommend and coordinate action on nuclear research, ensure that authorized assignments were carried out, and, within six months, prepare a final

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report on the feasibility of building atomic bombs.

Conant, acting as Bush’s representative, had oversight of the whole program. Briggs stayed on as chairman of the S-1 Section, with Dean Pegram of Columbia as vice chairman and a number of outstanding scientists serving as consultants. In addition, three program chiefs, each a Nobel Prize winner, were in charge of three distinct programs in physics. Arthur H. Compton of the University of Chicago headed the program of basic physics studies and measurements of nuclear properties pertinent to the chain reaction. His program also included exploring the problem of plutonium production by means of the controlled fissioning of uranium. Ernest 0. Lawrence of the University of California, Berkeley, had responsibility for producing the first small samples of fissionable elements, isotope separation by the electromagnetic method, and experimental work on the properties of plutonium. Finally, Harold C. Urey of Columbia University had charge of isotope separation by the diffusion and centrifuge methods, as well as research on heavy water production.

To supervise engineering procurement and production plant construction – activities that Bush and his associates knew must shortly be turned over to the Army – the OSRD director set up a planning board, headed by Eger V. Murphree, vice president of the Standard Oil Development Company, an affiliate of Standard Oil Company (New Jersey). The OSRD would enter into and finance all contracts negotiated in support of the reorganized atomic energy program. The board would make recommendations to Bush concerning those contracts for engineering, for development of the diffusion and centrifuge processes, and for the heavy water program. Briggs and Conant, with the interested program chiefs, would recommend all other contracts. When the Army took over administration of much of the atomic energy program, many OSRD contracts had to be renegotiated.38

America’s entry into World War II hastened the move for the Army to take over the primary direction and control of the bomb development project. Concrete steps to bring about this change came up for discussion at a meeting of the Top Policy Group called by Vice President Wallace on 16 December. In attendance were Secretary Stimson, Bush, Wallace, and, in addition, Harold D. Smith, director of the Budget Bureau. Conant and General Marshall were unable to attend. According to Secretary Stimson, that meeting was significant. The group discussed, he recorded, “some of the new inventions, many of them diabolical, that are coming out of the Scientific Research Commission” [NDRC] and “decided to go ahead with certain experiments.” Bush himself noted the group’s strong opinion “that OSRD should press as fast as possible on the construction of pilot plants.”39 He estimated this aspect of

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the work would cost $4 to $5 million and stated that the Army should take over when full-scale construction began, presumably when the pilot plants were ready. He recommended that a suitably trained Army officer should familiarize himself with the general nature of the program.

The Top Policy Group then approved Bush’s reorganization of the atomic energy program and his plans and recommendations for action. They also agreed that the international aspects were clearly a presidential responsibility, with Bush’s function limited to liaison solely on technical matters.40

Progress in Research and Development: The Nuclear Steeplechase

Two days later, on 18 December, the new OSRD S-1 Section held its first meeting, a session “pervaded by an atmosphere of enthusiasm and urgency.”41 Conant explained again the decision to proceed with the development of the bomb and stressed the necessity of a maximum effort. His words were seconded by Urey and Pegram, recently returned from England, who described British progress on the gaseous diffusion method of isotope separation and in experiments with heavy water. They also emphasized that Britain greatly feared Germany might produce atomic bombs before the Allies. Probably the most enthusiastic presentation was Lawrence’s description of his success in testing the electromagnetic method as a possible process for separating uranium isotopes. As a member of Compton’s reviewing committee the previous summer, Lawrence had become convinced of the great potentialities of this method in spite of the widely prevailing belief among scientists that the so-called space charge limitation – mutual repulsion of ions, making sharp focus of a beam of particles impossible – made it impractical for large-scale separation. Lawrence asserted that experiments at his Berkeley-based Radiation Laboratory with the mass spectrograph proved that the technical difficulties that tended to reduce the efficiency of the electromagnetic process could be overcome.42

A 184-inch cyclotron magnet, nearly five times wider than the 37- inch magnet used for previous experiments, had been under construction at the University of California, Berkeley, funded by the Rockefeller Foundation. Work had stopped because of the war, but now an extra appropriation from the foundation permitted Lawrence to complete the project by the end of May 1942, providing a means, as Lawrence wrote later, that “made it seem possible that we might be able to get somewhere … in time to be of value in this war.”43

With the Radiation Laboratory researchers concentrating increasingly on electromagnetic separation, most

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of the work on plutonium was left to Compton’s University of Chicago group that was investigating the feasibility of achieving a chain reaction. In January 1941, Compton decided to move the scientists working under his supervision at Columbia and Princeton to the University of Chicago. By early February, he concentrated the various research and development activities under what was called, for security reasons, the Metallurgical Laboratory. Compton’s group devoted itself henceforth to three main tasks: achievement of a chain reaction; study of the chemistry of plutonium, including development of a means for separating it from uranium; and the design of plutonium-producing piles. Because these tasks depended upon an adequate supply of uranium and graphite, representatives of the Metallurgical Laboratory also actively supported the S-1 Section’s planning board in the procurement program, contributing much to its success.44

At the same time, research on the gaseous diffusion process and on the production of heavy water went forward under Harold Urey’s direction at Columbia, and investigations on the centrifuge method of separation progressed under the general supervision of Eger Murphree at the University of Virginia, where physicist Jesse W. Beams directed the program, and at the Standard Oil Development Company in New Jersey, where research begun earlier at Columbia was continued.

Work was also proceeding on still another separation method, liquid thermal diffusion, based on the tendency of one of two isotopes in a fluid to concentrate near the hotter of two opposing surfaces. Philip H. Abelson had started research on this process at the Carnegie Institution but later moved to facilities at the Naval Research Laboratory. While development of the thermal diffusion process was not a part of the OSRD program, it would prove highly useful to the atomic project at a later date.45

Thus the OSRD was at work simultaneously on five methods of producing fissionable materials – three isotope separation processes (electromagnetic, gaseous diffusion, and centrifuge) for producing U-235 and two pile processes (uranium-graphite and uranium-heavy water) for manufacturing plutonium – projects Conant referred to as five “horses” in a race.46 Choosing a favorite and predicting an outcome, however, were almost impossible because any one of the horses might encounter insurmountable obstacles. Although concentrating all resources on the most promising horse would have been more efficient and economic, playing this odd just might have enabled Germany to be the first to build an atomic bomb.

In support of this nuclear steeplechase, the OSRD, by early February 1942, had entered into ten contracts with twelve institutions totaling more than $1 million, figures that roughly doubled in the next month. On the

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twentieth, Conant recommended that all five methods “be pushed vigorously” until 1 July, by which time he hoped many of the contracts could be dropped or revised in accordance with whatever progress had been made. Indeed, Conant continued, if by then the electromagnetic method of separation demonstrated a clear capability “of producing grams per day,” work on other methods of producing fissionable materials might be dropped or at least continued at a slower pace. Furthermore, even if all five horses had to be kept running “at full speed down the course” until the beginning of 1943, the OSRD research program might still be completed for between $10 and $17 million.47

The “intense scientific research and engineering planning now underway” was the subject of a guardedly optimistic progress report that Bush submitted to the President on 9 March. “The possibility of actual production appears more certain,” he wrote, but “the way to full accomplishment is still exceedingly difficult.” A full-scale effort might achieve completion of the project in 1944, or possibly six months sooner, and success for either the Allies or the enemy could “be determining in the war effort.” Bush pointed out that the work was “rapidly approaching the pilot plant stage,” with selection of the best methods of production not too far off. The summer of 1942, he believed, would “find the matter ready to turn over to Army control, for actual production plant construction.” A further reason for transferring “the whole matter ... to the War Department,” Bush added, was the necessity for instituting tight security measures once actual production began.48

With the Army’s entrance into the atomic energy program only a few months off, it was time to assign a suitable officer to follow nuclear developments. For this mission, General Marshall personally chose Brig. Gen. Wilhelm D. Styer, chief of staff of the Services of Supply (SOS). A graduate of the U.S. Military Academy, with an additional degree in civil engineering from Massachusetts Institute of Technology and two decades of experience as a Corps of Engineers officer supervising various kinds of construction projects, Styer was well qualified to lay the groundwork for Army participation in the atomic energy program. He immediately began an intensive study of the project, in close coordination with Bush and the S-1 Section. Despite the demands of his SOS duties, from this point until his departure for an overseas assignment late in the war, General Styer would play an important part in the Army’s effort to produce an atomic bomb.49

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The Army and the Atomic Bomb

Meanwhile, the five horses were in the running, four of them neck and neck, with a fifth one now bidding to join the race. This was the alternate method of producing plutonium by using heavy water instead of graphite as the moderator in a chain reaction pile, a process strongly championed by Urey. As work approached the pilot plant stage, the need to concentrate on one or more of these horses was becoming increasingly apparent. To conserve time, design and construction of actual production plants should begin even before the pilot plants were finished. However, Conant believed there was “a desperate need for speed” to build the bombs before the Germans could and he only solution was to go ahead on all five.50

On 23 May, S-1 Section Chairman Lyman Briggs met with Compton, Lawrence, Urey, and Murphree to make final recommendations on the program. In a report submitted to Bush two days later, the group concluded that practical atomic bombs of either U-235 or plutonium, with an energy release equal to that of several thousand tons of TNT, were definitely feasible. Underestimating the amount of fissionable material later found necessary for each bomb, as well as the time required for development and construction, they believed the bombs would be available in small quantities by about July 1944. They recommended funding of all five methods, although, for reasons advanced primarily by Compton, they gave the uranium-graphite pile a definite priority over the heavy water pile. They also proposed a pilot diffusion plant and preparation of complete engineering designs for a full-scale diffusion installation. They advised constructing a centrifuge plant by January 1944, an electromagnetic plant by late 1943, a plutonium-producing atomic power installation by early 1944, and, as an auxiliary to the latter, heavy water plants by May 1943.

Bush, Conant, and General Styer approved these recommendations and, on 13 June, Bush and Conant submitted them to the Top Policy Group with detailed plans to expand the atomic energy program. They underlined the danger of German success in building an atomic bomb and endorsed the proposal to continue work on all major methods of production. At the same time, they warned that such a course would interfere with other military research and called for careful judgment, when further study made it possible, to achieve a better balance.51

Importantly, Bush and Conant recommended that construction of the separation plants and development of the power project be turned over to the Army, specifically “to be in [the] charge of a qualified officer designated by the Chief of Engineers and reporting to him. ...” They also suggested that this officer be assisted on a full-time basis by leading civilian scientists and engineers, “preferably in the status of officers.”52 Funds for

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this work – $54 million in fiscal year 1943 – should be made available to the Engineers chief who, to avoid delay, should be authorized to spend or overobligate any money under his control with the understanding that he would be reimbursed later. After consulting with the S-1 Section’s planning board, the Engineers chief should also begin immediately to let contracts for the detailed design of all plants.

Under the Bush-Conant proposals, the OSRD would continue to direct and control research and development, with $31 million directly available for this purpose and an additional $5 million held in reserve for contingencies in the next fiscal year. There would be frequent meetings between representatives of the OSRD and the Corps of Engineers in order to coordinate and report on research, development, and construction. Research and development on the actual military uses of atomic energy would be under the Joint Committee on New Weapons and Equipment of the Joint Chiefs of Staff. In addition, Bush and Conant suggested that sites be selected, priorities established, and close security regulations imposed on the entire project.

With the approval of Vice President Wallace, Secretary Stimson, and General Marshall, Bush forwarded the proposed program to the President on 17 June 1942. “If you also approve,” he wrote, “we will proceed along these lines immediately.” The President’s initials – “OK FDR” – were affixed that day, signaling the decision to go ahead.53

The United States was now firmly and fully committed to an all-out effort to build an atomic bomb. From initial skepticism and only casual interest, the attitude of the government had changed gradually to one of active support. The ultimate decision to build the bomb was a presidential one and, as such, had been made at the meeting with Wallace and Bush on 9 October 1941. But laying the groundwork for that far-reaching decision were the intermediate steps taken by Bush and his scientific associates in early December 1941, reinforced by Stimson and Wallace later that month, and confirmed by members of the S-1 Section and the Top Policy Group in the spring of 1942. As for the Army, the President’s decision on 17 June brought it back into the atomic bomb program, this time to participate on a far broader scale. Within hours of that decision, the Army designated Col. James C. Marshall, who had nearly twenty-five years as a regular in the Corps of Engineers, to begin the task of organizing and carrying out its vast new assignment as administrator of all construction work for that program.