Anglo-American Atomic Cooperation, 1940-48

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Anglo-American Atomic
Cooperation 1940-1948
Gruffudd Llewelyn Ifor
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History (V100)
Dr Michael Hopkins
Word count:
Submitted on May 18th
, 2015

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Contents
List of Figures………………………………………………………………....……3
Introduction………………………………………………………………..………..4
Chapter 1: The changing nature of cooperation…………………………..……9
Chapter 2: Collaboration to non-cooperation………………………….....……33
Conclusion……………………………………………………………......…….…44
Bibliography………………………………………………...……………………..48

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List of figures
Figure 1 - A simplified chart showing the organisational structure of the
Manhattan Project from L. R. Groves, Now It Can Be Told: The Story of the
Manhattan Project (New York: Harper, 1962), p.2.
Figure 2 - Map showing the locations of the Manhattan Project’s main sites.
<http://content.wow.com/wiki/Manhattan_District> [accessed 2 May 2015]

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Introduction
“Great events have happened. The world is changed and it is time for sober
thought. It is natural that we should take satisfaction in the achievement of our
science, our industry, and our Army in creating the atomic bomb, but any
satisfaction we may feel must be overshadowed by deeper emotions.
The result of the bomb is so terrific that the responsibility of its possession
and its use must weigh heavily on our minds and on our hearts. We believe
that its use will save the lives of American soldiers and bring more quickly to
an end the horror of this war which the Japanese leaders deliberately started.
Therefore, the bomb is being used.
No American can contemplate what Mr. Churchill has referred to as ‘this
terrible means of maintaining the rule of law in the world’ without a
determination that after this war is over this great force shall be used for the
welfare and not the destruction of mankind.”
- H. L. Stimson, ‘Memorandum for the press’, August 9, 19451
The detonation of the atomic bombs ‘Little Boy’ and ‘Fat Man’ over the
Japanese cities of Hiroshima and Nagasaki by the United States in August
1945 remains the only use of nuclear weapons in the history of warfare. The
unprecedented scale of the destruction caused has led to prolonged disputes
1 Quoted in H. L. Stimson and M. Bundy, On Active Service in Peace and War (New York:
Harper and Brothers, 1948), p. 376.

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over the morality and wisdom of the use of these bombs, and continues to
divide opinions today.
Over the course of my dissertation I will explore the events that led up to this
cataclysmic course of action, as well as those that followed it, examining
closely the atomic cooperation between Great Britain and the United States of
America. I will assess the closeness of the relationship and deduce whether it
was a positive affiliation that benefited both countries in the long run, while
also observing the nature of the communication between them. While the
Manhattan Project is largely portrayed as an American achievement, British
scientists and their work had a significant influence on it. Up until late 1941,
British research was substantially ahead of that of the United States, and
British scientists made crucial breakthroughs that paved the way for further
discoveries. The Frisch-Peierls memorandum, for example, provided the
catalyst for an increased sense of urgency in their research, and led to the
creation of the MAUD committee, whose reports later inspired President
Roosevelt to approve an American atomic bomb project.
My study seeks to contribute to the existing literature by building on existing
works and filling a gap in the knowledge. By emphasising Britain’s role in the
Anglo-American atomic relationship of the 1940s, I will focus on the
importance of the early atomic research and the effect that it had later on. My
work is focused on the period 1940-48, as it is offers a clear idea of the
beginning and end of this period of Anglo-American atomic cooperation. The
period starts with Frisch-Peierls memorandum of 1940, which founded the

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basis of early British atomic research, and concludes at the Modus Vivendi of
1948, which saw the termination of the wartime agreements. While limiting the
period to 1940-46 and ending my work with the McMahon act of August 1946
was a possibility, I chose instead to finish with the Modus Vivendi, as I feel
that it is an agreement that not only signifies the end of this period of atomic
cooperation, but also the beginning of a new one, as it grants Britain access
to new atomic information that would prove important to their own
independent atomic bomb project.2
My work shall be divided into two chapters and will be arranged
chronologically, centring on the Quebec Agreement of August 1943. The first
chapter will look at the early collaborative relationship between Britain and the
United States, comparing and contrasting the changes in attitude that both
countries experienced as their roles changed during the early years of the
war. This chapter shall be the main focus of my work, as it covers a period in
which a significant power swing occurred in the Anglo-American relationship. I
will emphasise each nation’s individual desire for collaboration, firstly the
United States in 1941, and then the British in 1942, whilst also interpreting the
significance of the sea of mutual suspicions and misgivings that enveloped
atomic relations at the time. This chapter will explore the significance of the
early progress made by the British atomic research programme, before
moving on to assess the series of events that ultimately led to a collaborative
agreement between Great Britain and the United States.
2 “Modus Vivendi” of 1948: accord between UK, US and Canada on cooperation in field of
atomic energy, NA, PREM 11/786.

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My second chapter will begin with the Quebec Agreement of 1943, which saw
both nations agreeing “to bring the Tube Alloys project to fruition at the
earliest moments.”3 This agreement outlined the terms of the coordinated
development of the basic science and advanced engineering related to
nuclear energy and weapons. As a result, British atomic research was
subsumed into the Manhattan Project, signalling the beginning of a truly
combined effort. The second chapter will then look at the atomic relationship
between Britain and America throughout the rest of the war, which culminated
in the dropping of the atomic bombs ‘Fat Man’ and Little Boy’ on Hiroshima
and Nagasaki respectively. While the bombing of these Japanese cities
signalled the end of the Second World War, it did not signal the immediate
end of the Anglo-American atomic relationship. I will consider the
repercussions and consequences of the use of the atomic bomb, and the
effect that it had on the relationship between the two countries, and how
Anglo-American atomic collaboration was gradually disbanded. The Atomic
Energy Act of 1946, or the McMahon Act, which placed control of the nuclear
technology developed by the Manhattan Project firmly in American hands will
be examined closely, as it was a significant indicator of how the relationship
would deteriorate over the next fifteen months. I will close the chapter with a
focus on the Modus Vivendi of January 1948, in which the United States
signalled their intent to terminate the secret agreements that had been in
place since the war, as they believed them to be constrictive and in conflict
with their own interests.4 Upon agreeing on the Modus Vivendi, Britain and
3 Copy of Quebec Agreement 1943, National Archives (hereafter NA), FO 800/540.
4 “Modus Vivendi” of 1948: accord between UK, US and Canada on cooperation in field of
atomic energy, NA, PREM 11/786.

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America signalled the end of their first collaborative relationship, and gave
way to the birth of the next one.
While the United States was the driving force behind the success of the
Manhattan Project during the Second World War, it was Britain’s early
breakthroughs in atomic research that made the atomic bomb project
possible. This paper will argue that it was the early British work that led to the
success of Anglo-American atomic cooperation, and that it was American
isolationist behaviour towards the end of the period that led to the breaking up
of the relationship.5
5 J. Baylis, Anglo-American Defence Relations 1939-1984: The Special Relationship (London:
Macmillan, 1984), p. 32.

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Chapter One
The changing nature of cooperation
At the outbreak of war in 1939, physicists on both sides were fully aware of
the potential of nuclear fission, but remained unsure as to how it could be
utilised in a bomb. Although there was nothing to show that it was impossible,
neither was there incontrovertible evidence that it was possible.6 In January,
Austrian physicist Otto Robert Frisch had experimentally confirmed Otto Hahn
and Fritz Strassman’s discovery of nuclear fission, but the prospect of using it
in warfare remained a distant fantasy. Charles Percy Snow, the editor of
popular British journal Discovery, wrote in September 1939 that if the idea
were practicable it would be a watershed moment for scientific influence on
warfare.7 The general attitude towards the feasibility of utilising nuclear fission
as a weapon can be summed up in the MAUD Report of 1941, which states
that those involved in the MAUD committee “entered the project with more
scepticism than belief”.8 However, the further that atomic research
progressed, the more that scepticism began to wane, and as the possibility of
creating weapons of mass destruction began to look real.
The completion of the Frisch-Peierls memorandum in March 1940 provided a
clear technical exposition of a nuclear weapon for the first time, and with it a
real sense of urgency into British research. Otto Frisch and Rudolf Peierls,
6 L. A. Turner, Reviews of Modern Physics, Vol. 12, No. 1 (January 1940)
7 C.P. Snow, ‘A New Means of Destruction?’ Discovery, New Series, Vol. II, No. 18
(September 1939), p. 443.
8 Report of M.A.U.D. Committee, NA, AB 1/238

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two refugee scientists working at the University of Birmingham, recognised
the destructive capability that an atomic bomb would possess, and believed
that it was imperative that research efforts be increased. In their report they
“suggested how U-235 could be separated, analysed the critical size of a
bomb, discussed how it could be detonated, and predicted the enormous
radiation effects”, all of which served to catch the eye of a certain Henry
Tizard, who was the chairman of the Committee on the Scientific Survey of Air
Warfare (CSSAW).9 Margaret Gowing stated in her 1964 work, Britain and
Atomic Energy, that it was the “first memorandum in any country which
foretold with scientific conviction the practical possibility of making a bomb
and the horrors it would bring”.10 Gowing’s glowing assessment of the Frisch-
Peierls memorandum underlines its importance in its field. Without any
experimental aid, these two scientists had been able to correctly predict the
applied possibility of harnessing nuclear fission to create a bomb, bringing up
and answering important new questions, such as “What fraction of collisions
between neutrons and uranium-235 nuclei would lead to fission?”11 German
physicists working on a similar project for the Nazi government did not ask the
same questions at all, and subsequently made little progress in their
endeavours. Indeed, the noted theoretical physicist Werner Heisenberg
refused to believe that an atomic bomb was possible, even after it was
reported that the Allies had dropped one on Japan. In a conversation with
Otto Hahn, who discovered nuclear fission, he stated:
9 A. J. Pierre, Nuclear Politics: The British Experience with an Independent Strategic Force,
1939-70 (London: Oxford University Press, 1972), p.14.
10 M. Gowing, Britain and Atomic Energy, 1939-45 (London: Macmillan, 1964), p. 42.
11 Ibid.

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“I am willing to believe that it is a high pressure bomb and I don’t believe that
it has anything to do with uranium, but that it is a chemical thing where they
have enormously increased the whole explosion.”12
Frisch and Peierls’ work paved the way for further progress in atomic
research, showing an incredible scientific breadth that was unparalleled at the
time. The questions they raised and answered in their memorandum were
unprecedented in their field, as evidenced by the fact that the Germans did
not come close to answering them over the course of the war. It should also
be noted that the Americans did not make the same queries for months
afterwards, and even then it was only after the British work was made
available. Stephane Groueff states that Peierls’ confidence that an atomic
bomb was possible “had been an important factor in convincing American
scientists in the early days.”13
In the conclusion to their memorandum, Frisch and Peierls stated that “it must
be realized that no shelters are available that would be effective and that
could be used on a large scale.” Making the assumption that the Germans
were already in the process of building an atomic bomb, they made it clear
that they believed that the most effective defence would be a counter-threat
with a similar bomb. Therefore, they strongly advocated a significant increase
12 L. Groves, Now It Can Be Told: The Story of the Manhattan Project (New York: Harper,
1962), p. 334.
13 S. Groueff, Manhattan Project: The Untold Story of the Making of the Atomic Bomb
(Boston: Little Brown, 1967), p. 209.

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in atomic research, and for production to start on a weapon as soon as it was
possible, stressing its extreme urgency.14
Their memorandum was passed on to Henry Tizard via Marcus Oliphant, who
was the professor of physics at the University of Birmingham. Tizard then sent
it on to G. P. Thomson, who was in charge of uranium research within the
CSSAW. This ultimately led to the establishment of the MAUD committee to
investigate the feasibility of producing an atomic bomb. Upon reading the
Frisch-Peierls memorandum, Thomson asked the CSSAW for permission to
discuss it with Professor John Cockcroft, who worked for the Ministry of
Supply, and Professor Oliphant.15 Informal enquiries were made via Professor
A. V. Hill, who was an attaché to the British Embassy in Washington DC, to
see how American atomic research was progressing.16 The news from the US
was that the Americans believed that research into uranium, whilst most
interesting scientifically, was not deemed a priority as a line of research in
wartime. Despite these misgivings, a uranium sub-committee of the CSSAW
was set up, with Thomson as its chairman. By June, the CSSAW no longer
existed, and the committee existed independently within the Ministry of
Aircraft Production. However, even before its independence from the CSSAW,
it was decided that a less conspicuous name was required for the committee,
and following the misinterpretation of a message from Danish physicist Niels
14 Frisch-Peierls Memorandum, March 1940, reproduced at
<http://www.atomicarchive.com/Docs/Begin/FrischPeierls.shtml> [accessed 26 May 2015]
15 Gowing, Britain and Atomic Energy, p.43.
16 Pierre, Nuclear Politics, pp. 13-4.

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Bohr to his former colleague Otto Frisch, the code name ‘MAUD’ was decided
upon.17
The MAUD committee met for the first time on the 10th of April, and began its
research on fast fission and isotope separation. As well as G. P. Thomson,
the committee consisted of Marcus Oliphant, John Cockcroft, Philip Moon,
James Chadwick, and Patrick Blackett. Despite the fact that it was their paper
that had inspired the creation of the MAUD committee, Frisch and Peierls
were excluded from it on the basis that refugees could not be included in
scientific wartime work. While Peierls had become a naturalised citizen in
February 1940, Frisch was still classified as an enemy alien, which made it
nearly impossible for them to be part of a top-secret committee. In an
interview in August 1969, Peierls stated that “people think [during] wartime
[that having] an enemy sitting on the committee that conceivably might
discuss some delicate information [is] the wrong thing”, which was a
reasonably accurate assessment of the attitudes in Britain at the time, despite
the fact that he quite clearly was not an enemy.18 Gowing states that ‘the
international ramification[s] of science were mistrusted’, and gives an example
of how Frisch could vaguely be connected to Professor Otto Hahn, who was
still in Nazi Germany, further proof of the increased vigilance that such a
17 Niels Bohr, who had undertaken some important research on uranium, sent Frisch a
telegram from German-occupied Denmark. The telegram signed off with ‘Tell Cockroft an
Maud Ray Kent’, the final three word of which were misinterpreted as being an anagram for
‘radium taken’, and evidence for Germany’s advancement in the field of atomic research. In
later years it was made evident that Maud Ray was a former governess of Bohr’s children
who lived in Kent.
18 Sir Rudolf Peierls to C. Weiner, 12 August 1969, American Institute of Physics, reproduced
at <http://www.aip.org/history/ohilist/4816_2.html> [accessed 29 April 2015]

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covert operation required.19 20 Although a case could be made for the pair’s
exclusion from the committee on the grounds of a possible security breach, in
terms of completing the work in the shortest possible time, it made no sense
whatsoever. Peierls wrote to the chairman of the committee, whose identity he
did not know, stating that both Frisch and himself would be able to answer
many of the questions that would be raised, and pointing out the futility of
trying to keep their own secret from them. Upon reading this letter, Thomson
decided that both scientists, although not members of the committee, should
be consulted on its matters.
When Thomson met with Frisch and Peierls for the first time, Peierls pointed
out to him that separating the uranium-235 isotope was their biggest obstacle,
and urged that Professor Franz Simon be brought in to work on it. In June,
Simon, a German physicist, physical chemist and thermodynamicist working
in the Clarendon Laboratory at the University of Oxford was commissioned to
investigate the viability of separating uranium-235 by gaseous diffusion.
Simon had fled Germany in 1933 in order to escape the increasing anti-
Semitism that ensued following the rise to power of Adolf Hitler and the Nazi
party, as had many other renowned scientists such as Leo Szilard, Albert
Einstein and Hans Bethe. This exodus of scientists would eventually prove
extremely costly to the German war effort, as many of them proved invaluable
to the Allies’ scientific programmes, most notably the Manhattan Project.
19 Frisch had worked closely with his aunt Lise Meitner, and although she had fled Germany
for Stockholm, she had worked in close proximity with Hahn.
20 Gowing, Britain and Atomic Energy, p.46.

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By December 1940, Simon had completed his research, and concluded that
isotopic separation was indeed possible. His work included technical
specifications and cost approximations for a sizeable uranium enrichment
plant. James Chadwick, who wrote the report's final draft, later noted that
when he "realised that a nuclear bomb was not only possible, it was
inevitable”, he had to start taking sleeping pills, maintaining that it was the
only remedy.21
During the autumn of 1940, Henry Tizard, accompanied by John Cockcroft,
led a mission to Washington DC in order to exchange scientific information
with the Americans.22 They discovered that American research was not
proceeding as quickly as the British work, and that it was in fact several
months behind.23 Cockcroft was of the opinion that the US was not devoting
sufficient time and resources to their research on uranium, and believed they
should employ a more vigorous approach. As it was clearly beneficial to both
countries that there should be closer contact as well as further exchange of
information between their scientists, an agreement was concluded. In the
spring of 1941 it was decided that there would be a British Central Scientific
Office attached to the British Supply Council in Washington, and in turn, a
Liaison Office for the American National Defense Research Council (NDRC)
was established in London.24
21 Sir James Chadwick to C. Weiner, 20 April 1969, American Institute of Physics, reproduced
at <http://www.aip.org/history/ohilist/3974_4.html> [accessed 29 April 2015]
22 V. Bush, Modern Arms and Free Men: A Discussion in the Role of Science in Preserving
Democracy (New York: Simon & Schuster, 1949), p. 39.
23 R. Rhodes, The Making of the Atomic Bomb (New York: Simon & Schuster, 1986), p. 337.
24 Gowing, Britain and Atomic Energy, pp. 64-6.; S. H. Paul, Nuclear Rivals: Anglo-American
Atomic Relations 1941-1952 (Columbus, OH: Ohio State University Press, 2000), p. 19.

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The British knew that if they wanted their atomic research project to succeed,
it was crucial that they got the Americans on board. While they felt that an
atomic bomb was an urgent need, the United States thought otherwise,
remaining unconvinced that it was even possible. However, in his capacity as
part of the liaison team in England, Harvard nuclear physicist Kenneth
Bainbridge sat in on a meeting of the MAUD committee in April, and
discovered that they were at an advanced stage in their research. They were
convinced that the work undertaken on the development of the atomic bomb
had gone beyond the realm of speculation, and Bainbridge commented that
the committee had “a very good idea of the critical mass and [bomb] assembly
[mechanism].”25 His subsequent report on the meeting ultimately led to a
report by Nobel Prize winning physicist Arthur Compton in May, which stated
that an atomic bomb was possible, but not before 1945, whilst also
emphasising uranium’s possible capabilities in producing energy.26 27
John Cockcroft’s visit to Enrico Fermi’s laboratory at Columbia University in
the autumn of 1940 had shown that the Americans’ uranium research was
focused on atomic energy rather than the atomic bomb, and Compton’s
findings would do nothing to change that.28 Given that Britain did not have the
resources necessary for such a bomb, they were heavily reliant on the
Americans. While the Americans were undoubtedly behind in terms of overall
research, they possessed more elaborate apparatus than their British
counterparts, and therefore were able to conduct experiments much more
25 Rhodes, Making of the Atomic Bomb, p. 337.
26 Compton was appointed the head of a review committee under the NDRC by Vannevar
Bush in April 1941.
27 Paul, Nuclear Rivals, pp. 20-1.
28 Gowing, Britain and Atomic Energy, p. 65.

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efficiently. As a country at war and under siege from the Germans, Britain’s
resources were becoming more and more strained, which made it increasingly
hard for the atomic research programme to make the necessary progress.
This led British scientists to look to the United States and its ‘immense
productive capacity’ to undertake expensive development work, and before
long the MAUD committee was deliberating the option of moving the main
developmental work over the Atlantic.29
After 15 months of intense work, the MAUD committee culminated in the
production of two reports in July 1941. They were titled ‘Use of Uranium as a
Source of Power’, and ‘Use of Uranium for a Bomb’. The conclusions and
recommendations of the MAUD committee’s reports were as follows:
1. The committee considers that the scheme for a uranium bomb is
practicable and likely to lead to decisive results in the war.
2. It recommends that this work be continued on the highest priority and
on the increasing scale necessary to obtain the weapon in the shortest
possible time.
3. That the present collaboration with America should be continued and
extended especially in the region of experimental work.30
The MAUD committee’s reports stated that a weapon could be made with 25
pounds of pure uranium-235, and that it would be ‘equivalent as regards
destructive effect to 1,800 tons of T.N.T.’, which was used as the yardstick for
29 Gowing, Britain and Atomic Energy pp. 66-7.
30 Report of M.A.U.D. Committee, NA, AB 1/238

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explosive comparison throughout the course of research on the atomic
bomb.31
The report detailed that they were still exchanging information with the
Americans, and that some laboratory work had been carried out on Britain's
behalf across the Atlantic. It came to the same conclusion that the Tizard
mission had done, namely that work undertaken in both countries should be
shared. The MAUD report also entertained the possibility that the uranium-
235 separation plant could well be located in the United States, and stated
that a trip to discuss the option would soon be underway, an indication that full
collaboration was most certainly on their minds.32
However, the Americans did not necessarily reciprocate the MAUD
committee’s enthusiasm for wide-scale collaboration. As they were not
militarily involved in the war, they had no urgent reason to pursue the
possibility of producing an atomic bomb. When Franz Simon was
commissioned to undertake his research on gaseous diffusion in the summer
of 1940, the committee had assigned R. H. Fowler to send progress reports to
the director of the American Uranium Committee, Lyman Briggs. Despite the
significant findings of Simon and the rest of the committee’s work, by August
of 1941, a month after the completion of the MAUD report, they still had not
received any response. While the United States did not receive an official
copy of the MAUD report until October, Charles C. Lauritsen, a Caltech
physicist, was in London with the NDRC and present at the meeting where the
31 ibid.
32 ibid.

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report was presented. He relayed the information to Vannevar Bush, the head
of the newly formed Office of Scientific Research and Development, to whom
the NDRC now reported to upon his return to the US a week later, but failed to
provoke a reaction. Lauritsen’s report stated that the MAUD committee had
concluded that due to the risk of aerial bombardment, as well as the costs, it
would be extremely difficult, if not impossible, to undertake the atomic bomb
project in Britain, and that many of the committee members believed that the
United States should take on the project.33 This is further indication of the
importance that the committee placed on the Americans’ ‘immense productive
capacity’, and their belief that full cooperation would be an essential element
in the atomic bomb project and any success that it might have.34
In August Marcus Oliphant, who was travelling to the US to discuss the radar
development program, was assigned to find out why their findings were not
being acknowledged. He visited Lyman Briggs and was extremely critical of
him:
“I called on Briggs in Washington [DC], only to find out that this inarticulate
and unimpressive man had put the reports in his safe and had not shown
them to members of his committee. I was amazed and distressed.”35
Whereas previous efforts to persuade the United States to shift their focus
from atomic energy to the atomic bomb had adopted a more patient approach,
33 Paul, Nuclear Rivals, p. 22.
35 M, Oliphant, ‘The Beginning: Chadwick and the Neutron’. Bulletin of the Atomic Scientists
38:10 (December 1982), pp. 14-8.

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Oliphant had no such tolerance. Samuel K. Allison, a member of Briggs’
committee recalled how he came to a meeting and told them in no uncertain
terms that a bomb should be their priority.
"He told us we must concentrate every effort on the bomb, and said we had
no right to work on power plants or anything but the bomb. The bomb would
cost 25 million dollars, he said, and Britain did not have the money or the
manpower, so it was up to us."36
The MAUD report, coupled with Oliphant’s visit, had a profound effect on the
nature of American atomic research, and led to a re-examination of their
approach towards uranium.37 Oliphant’s impact was such that Leo Szilard, the
Hungarian-American physicist who played an important role in kick-starting
American research into nuclear fission, commented after the war:
“If Congress knew the true story of the atomic energy project, I have no doubt
but that it would create a special medal to be given to meddling foreigners for
distinguished services, and Dr Oliphant would be the first to receive one.”3839
Attitudes had changed, and the feasibility of an atomic bomb had become
apparent, thus spurring the Americans into action. Although Bush remained
largely passive until Thompson forwarded an official copy of the report in
October, he then used it to win the support of President Roosevelt for a
36 Rhodes, The Making of the Atomic Bomb, p. 373.
37 Pierre, Nuclear Politics, pp. 22-3.
38 The Einstein-Szilard letter of August 1939 explained the possibility of atomic weapons, and
warned that Germany had already begun work on such weapons. The letter encouraged the
establishment of a US atomic bomb program, and signalled the beginning of what would
eventually turn into the Manhattan Project.
39 Rhodes, Making of the Atomic Bomb, p. 372.

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nuclear project.40 On the 11th of October, Roosevelt cabled Churchill
suggesting a coordinated, or ‘jointly conducted’ atomic program, a suggestion
that did not go down well in London.41 Although the MAUD report had strongly
advocated a combined project with the United States, Lord Cherwell,
Churchill’s atomic energy adviser did not agree, suggesting that the power
that the bomb would possess would give its holder unprecedented influence
over the rest of the world, and that it was therefore desirable for it to be an
independent undertaking.42 Despite acknowledging the difficulties that would
surround the construction of a uranium plant in Britain, as British research
was ahead of the Americans’, he believed it unwise and unnecessary to allow
them in on it, stating that he was ‘very much averse’ to putting the country at
the mercy of the United States.43 Following endorsement of the project by the
Chiefs of Staff, the British atomic bomb project was formed, and was assigned
the code name ‘Tube Alloys’.
In November, American scientists Harold Urey and George Pegram visited
Great Britain on a diplomatic mission in a further attempt to establish
cooperation on the atomic bomb project. While they were both impressed by
the progress of Britain’s research, they found themselves having to defend the
United States’ objectives in the face of accusations that they were entirely
focused on the potential of atomic energy rather than the creation of an
atomic bomb.44 Another concern that the British had about any potential
collaboration was that the United States would not be able to preserve the
40 Pierre, Nuclear Politics, p. 23; Paul, Nuclear Rivals, p. 22.
41 President to Prime Minister, October 11, 1941, NA, AB 1/207.
43 Cherwell to Prime Minister, August 27, 1941, NA, AB 1/170.

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secrecy of any such project due to them not being at war. They were
extremely wary of the danger of any information leaking to the Germans, as
they would then be able to accelerate their own atomic bomb project.
Considering the enormity of the project, as well as the impact that its success
could have, secrecy was absolutely essential, and as such the British were
right to be wary.45
A further report from Compton and the National Academy of Sciences on
November 27th served to convince Bush that a joint project was most certainly
in the Americans’ best interests. However, Britain still held back, as evidenced
by the two months that it took Churchill to respond to Roosevelt’s October
suggestion of a ‘jointly conducted’ effort.46 Even then, Churchill’s response
only came after the Japanese attack on Pearl Harbor, when it was clear to
him and his advisers that the Anglo-American alliance was about to be
formalised, and therefore pertinent to ensure that Britain did not alienate itself
from the Americans.47
By the late spring of 1942, Britain faced the stark realisation that the
Americans’ research had now surpassed theirs.48 A visit to the United States
by Wallace Akers and Professors Halban, Peierls and Simon from the Tube
Alloys Technical Committee had reported on the impressiveness of the
Americans’ uranium research labs, and made the British recognise the

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progress that they had made in a relatively short period of time.49 In addition,
when the US army took control of the Manhattan Project, security was
tightened, and the flow of information to Britain dried up. Soon they would be
faced with the tough decision of whether to soften their stance on
collaboration, or stay strong, and face the possibility of failure in their
endeavours. While Cherwell remained confident that Britain could
successfully conduct their own atomic bomb project during the course of the
war, despite the massive constraints on both finance and manpower, others
were more realistic.
On the 30th of July, the Lord President of the Council, John Anderson made
the following statement to Churchill:
“Sir… We must face the fact that… [our] pioneering work is a dwindling asset
and that, unless we capitalise it quickly, we shall be outstripped. We now have
a real contribution to make to a ‘merger’. Soon we shall have little or none.”50
Over the course of a year, both nations’ roles had been reversed, with the
British now the ones actively seeking collaboration while the Americans tried
to distance themselves. As signalled by Anderson’s statement, Britain was
now in real danger of seeing the possibility of participating in a successful
atomic bomb project pass them by. Michael Perrin, the secretary general of
the Tube Alloys project, commented upon his arrival in the US in June that
49 Akers was the director of the Tube Alloys project, while also holding the position of
research director for British chemical company Imperial Chemical Industries.
50 J. B. Bernstein, ‘The Uneasy Alliance: Roosevelt, Churchill, and the Atomic Bomb, 1940-
1945’, The Western Political Quarterly (University of Utah) 29.2 (June 1976), pp. 202-30.

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they were not far from completely outstripping Britain in every aspect of
atomic energy and that when they did, the would ‘see no reason for our
butting in.’51 The Americans were fully aware of the huge progress that they
were making, and as such were no longer so eager to pursue a combined
project, which posed a problem for the British.
As soon as realised that an atomic bomb could realistically be built before the
end of the war, and that they could develop it with very minimal British
assistance, the Americans began to distance themselves from any sort of
collaboration. The proposed transfer of the French physicist Hans von
Halban’s team to work in parallel with Compton’s team in Chicago was vetoed
by Vannevar Bush on the grounds that it would compromise the ‘narrow
vertical American secrecy organization.’52 Despite this resistance from Bush,
the British still considered the decision on whether or not the two nations
would collaborate to be in their hands. Evidence of this came with Anderson’s
letter to Bush on the 5th of August. In this letter he explained that as Britain
would not be able to complete their proposed diffusion plant within two years,
both Churchill and himself had decided that the plant should be constructed in
the United States. This plant, whose design and construction would be the
responsibility of the Americans, would then be added to their atomic program.
Additionally, he proposed the transfer of several key British researchers
including Simon and Peierls to work alongside the American project, with the
52 Halban to Akers, May 13, 1942, NA, AB 1/357.

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expectation that they be added to Dr James Conant’s executive committee.53
54
Bush’s reply, which came four weeks later, was an extremely diplomatic one,
just as Churchill’s reply to Roosevelt’s cable in late 1941 suggesting a ‘jointly
conducted’ atomic program had been.55 However, a follow up memo that he
sent on the 1st of October regarding the building of a British diffusion plant in
the United States was not quite so. In it, he ‘emphatically turned down’ the
idea, stating that it was not possible as the American atomic project had been
put under the supervision of the army.56
In September 1942, the Manhattan Project had been placed under the control
of General Leslie Groves, with the promise of the highest priority AAA rating
on necessary procurements.57 The project was set up in such a way that
Groves was central to all developments, and both Bush and Conant were
pushed to one side. In his role as Secretary of War, Henry Stimson instigated
the creation of the Military Policy Committee, which consisted of Bush,
Conant, Admiral W. R. E. Purnell from the Navy, and General Wilhelm D.
Styer of the Army.58
53 Dr. James Conant was the chairman of the NDRC, and an important figure within the
American atomic project. He was not in favour of combining their work with that of the British.
57 Groves, Now It Can Be Told, p. 16.
58 Groves, Now It Can Be Told, pp. 21-3.

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Figure 1:
A simplified chart showing the organisational structure of the Manhattan
Project from L. R. Groves, Now It Can Be Told.
Groves had a reputation for being a resolute character who got the job done,
and was determined to oversee a successful project. He was horrified to
discover how many people knew about parts of the project that were outside
their own individual areas, and set about the compartmentalising of it. During
a November visit to the United States; Tube Alloys director Wallace Akers
commented that he did not believe that the scientists involved with the project
would accept Groves’ airtight security measures, and that they would
cooperate with the British.59 Additionally, he believed Bush and Conant to be
unhappy with the restrictions placed upon the project by the army, when in
fact they were pleased to be supplied with an excuse for their lack of
59 Akers to Perrin, November 16, 1942, NA, AB 1/128.

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collaboration with the British.60 61 What Akers did not comprehend was that
Groves’ security policies were directed as much towards the British as they
were towards the Germans. By December, the Americans did not believe that
they needed British assistance to be able to build an atomic bomb. While they
acknowledged that an ending of cooperation would certainly delay the
process, they believed it could still feasibly be completed before the end of
1945.62 This made the sharing of information with the British both
unnecessary and unwise, and therefore pertinent to push forward with a policy
of noncollaboration.
However, Martin Sherwin argues that the main reason for this push towards a
cessation of cooperation was that any continuation would not be in the United
States’ best interests after the war.63 If they were to replace the British as a
dominating world power after the war, collaboration with them would be
counterintuitive. As Britain was a once great power on the decline, it was in
the Americans’ best interests to facilitate that decline, rather than show
solidarity towards them. They had, as Lord Cherwell had done in 1941,
recognised the overwhelming power that an atomic bomb would give them,
and did not intend to allow Britain to ‘cling to American coattails as it was
edged aside.’64 Churchill’s atomic energy adviser’s worst fears were now
60 As Groves was renowned as a strict regulator of others, and held a more senior position
than both Bush and Conant in the Manhattan Project, it was easy for them to shift the blame
for anything that displeased the British by claiming that the order had come ‘from above’. This
also served to bring Akers to the conclusion that the American scientists did not agree with
Groves’ methods, giving him confidence that they would only be temporary measures.
61 Akers to Perrin, November 5, 1942, NA, AB 1/357.
63 M. Sherwin, A World Destroyed: The Atomic Bomb and the Grand Alliance (New York:
Alfred A. Knopf, 1975), p. 172.
64 J. Hershberg, James B. Conant: Harvard to Hiroshima and the Making of the Nuclear Age
(New York: Alfred A. Knopf, 1993), p. 183.

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being realised, as he had predicted in August 1941: the British could well find
themselves ‘completely at [the Americans’] mercy’ if they were completely
excluded from further atomic developments.65
During the Trident Conference in Washington in May, Churchill received a
note from Anderson, which stated that the United States had agreed a
contract with Canada to purchase the entire output of their uranium mines as
well as their entire production of heavy water.66 This American monopoly on
Britain’s only feasible source of both of these resources served to end any
lingering notions that they could conduct their own independent program, and
made reaching an agreement on collaboration an even more urgent
requirement. Churchill, a man renowned for his bullish, uncompromising
nature, was forced to swallow his pride and sent various telegrams to Harry
Hopkins, Roosevelt’s trusted advisor, before sending the following to the
President on the 9th of July:
“Since Harry’s telegram of 17th June I have been anxiously awaiting further
news about Tube Alloys. My experts are standing by and I find it increasingly
difficult to explain delay. If difficulties have arisen, I beg you to let me know at
once what they are in case we may be able to help in solving them.”67
This clear indication of the importance of the matter to the British left
Roosevelt with an increasingly tough decision. In the context of the war, he
could not afford to alienate Churchill, as he still needed his cooperation for the
65 Cherwell to Prime Minister, August 27, 1941, NA, AB 1/170.
66 Lord President to Prime Minister, May 15, 1943, NA, PREM 3/139/8A.
67 Prime Minister to Hopkins, July 9, 1943, NA, PREM 3/139/8A.

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proposed invasion of Nazi controlled Europe, which he hoped to launch from
Britain itself. Following discussion with Hopkins on the issue, Roosevelt wrote
to Bush on July 20th declaring his wish that ‘the full exchange of information
with the British Government regarding tube alloys’ be resumed. While it was a
decision that may not have been in the best interests of the United States in
terms of the atomic bomb project, he believed it to be in their best interests in
the wider context of the war.68
Although it is true that it was the United States who did a significant portion of
the developmental during the first phase of the Manhattan Project, between
1940 and 1943 Britain more than played its part as well. The Frisch-Peierls
memorandum, as well as Franz Simon’s work for the MAUD committee, was
crucial in both kick-starting the atomic research program and in providing a
solid base for further work. While the Americans provided the industrial
workforce and the funding needed to carry out their objectives, British
scientists undertook a large amount of the research work. In the case of the
mooted separation plant for the production of uranium-235, there were
discussions in the spring of 1941 about doing all of the research work in
Britain, and the large-scale development work in the United States.69 Although
this idea failed to materialise, it does confirm the continuing influence of the
British in terms of experimental work.
The Americans however, did not acknowledge the significance of the stimulus
that Britain’s early research had provided to their project, nor the impact that
68 Hershberg, James B. Conant, pp. 188-9.
69 Gowing, Britain and Atomic Energy, pp. 73-4.

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the MAUD report had had, which made the British feel underappreciated. As
they believed themselves to be a vital component of any combined project,
Britain were perhaps not as tactful as they could have been in their approach,
and could have been careful not to antagonise the volatile character that was
Groves. However, it was not altogether unreasonable for them, as the nation
that had provided the majority of the initial research work to demand parity
with the United States on the Manhattan Project. While it did not give them
equal status, the Quebec Agreement certainly improved the standing of the
British in their collaboration with the Americans.

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Chapter Two
Collaboration to non-cooperation
Churchill and Roosevelt signed the Quebec Agreement on the 19th of August
1943, agreeing to collaboration between Britain and the United States on the
matter of Tube Alloys. They established five separate points, one of which
was that Britain would cede control of the commercial rights to atomic energy
to the Americans.70 This decision had been made by Churchill in July, prior to
his meeting with Stimson, in a further attempt to obtain approval for a
combined project that Roosevelt had already approved. Both Anderson and
Cherwell had expressed their belief that atomic energy would not hold any
significance in any potential industrial application, and had supported the
ultimately unnecessary sacrifice of what would later prove to be an important
economic asset.71
The other significant undertaking of the Quebec Agreement was the
establishment of the Combined Policy Committee ‘to ensure full and effective
collaboration between the two countries in bringing the project to fruition’.72 It
was agreed that the committee would consist of Stimson as its chairman,
Bush, Conant, the British representatives Colonel Llewellin and Field Marshal
70 ‘Appendix 4: The Quebec Agreement’ in Gowing, Britain and Atomic Energy, pp. 439-40.
71 Akers to Perrin, August 19, 1943, NA, AB 1/376.
72 Appendix 4: The Quebec Agreement’ in Gowing, Britain and Atomic Energy, pp. 439-40.

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Dill, as well as the Canadian representative C. D. Howe.73 The committee met
for the first time on the 8th of September, when they established the Technical
Subcommittee.74 In the two years between its forming and the dropping of the
atomic bombs on Japan, the CPC only met eight times, but despite this,
achieved much in this time, such as the establishing of the Combined
Development Trust in March 1944.75 76
Groves was a tough, single-minded character, and did not take well to being
rushed, therefore he was not best pleased when Akers instructed that
Chadwick, Simon, Peierls and Oliphant should be sent over to the United
States before the CPC had put the necessary security protocols in place.77
This placed further strain on an already uncertain relationship. Due to his
position within ICI, the Americans did not trust Akers, believing that his
objective was to corner the atomic business for his company.78 In December
Akers arrived in the United States with a diffusion team consisting of fifteen
British scientists, while Chadwick, Oliphant and Peierls also came to take up
permanent residence.79 Chadwick, in his roles as technical advisor to the
CPC and head of the British mission was in many ways the antidote to Akers,
and was able to establish a good relationship with Groves. He was discerning
73 Llewellin was the Minister of Aircraft Production, while Dill, in his capacity as Churchill’s
personal representative was the Senior British Representative on the Combined Chiefs of
Staff.
74 American Major General Wilhelm Styer chaired the Technical Subcommittee, and its
members consisted of James Chadwick, Groves’ scientific advisor Richard Tolman, and C. J.
Mackenzie, who was the head of the Canadian National Research Council. The committee
was able to act without the approval of the CPC if its decision was unanimous.
75 The Combined Development Trust was a joint Anglo-American-Canadian venture created
to deal with issues surrounding the raw materials needed for the Manhattan Project.
76 Groves, Now It Can Be Told, pp. 170-6; Gowing, Britain and Atomic Energy, pp. 234-5.
77 Paul, Nuclear Rivals, pp.57-8.
78 Gowing, Britain and Atomic Energy, p. 172; ibid, p. 176; Paul, Nuclear Rivals, p. 59.

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enough to recognise that the head of the Manhattan Project would be crucial
for any possible post-war collaboration, and thus ensured that he did
everything in his power to make the relationship run smoothly.80
Figure 2:
Map showing the locations of the Manhattan Project’s main sites.
Chadwick realised that if Britain were to undertake a major atomic project
after the war was over, it would be advantageous for them to have as many
scientists as possible in the United States. After the Quebec Agreement was
signed, he had visited each of the main atomic energy research centres, and
was mightily impressed by the extent of the Americans’ progress.81 He
realised that the British contributions to the Manhattan Project henceforward
80 Chadwick to Anderson, February 22, 1945, NA, FO 800/524; Gowing, Britain and Atomic
Energy, pp. 236-8.
81 Pierre, Nuclear Politics, p. 51; Gowing, Britain and Atomic Energy, p. 241.

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were far from crucial, and therefore reasoned that they should try and gain as
much knowledge as possible from their involvement. As a result, he urged
that the best scientific minds available be transferred to America, regardless
of whether or not they were involved with Tube Alloys.82 83 Given the huge
scale of the project, as evidenced by Figure 2, British scientists were
distributed all over America, and rarely got to see the part that they were
working on in its entirety. The British recognition that the part that they played
in the Manhattan Project would be subsidiary to the American contribution
was received favourably by Groves. In fact, he attributed it as being largely
responsible for the success of the Combined Policy Committee, referring to it
as “awareness on the part of the British delegates of the magnitude of the
American contribution in comparison to theirs.”84 The British had learnt from
their early mistakes in dealing with Groves, and had recognised that he was
an individual who needed to be dealt with carefully. Acknowledging the role
that he might play in any post-war collaboration, they were keen to do
whatever they possibly could to maintain a positive relationship.
Post-war collaboration was agreed following a meeting between Churchill and
Roosevelt at the President’s Hyde Park residence in New York on the 17th
and 18th of September 1944. The Hyde Park Aide-Memoire was signed,
detailing that “full collaboration between the United States and the British
Government in developing Tube Alloys for military and commercial purposes
should continue after the defeat of Japan unless and until terminated by joint
82 Scientists sent over to the Manhattan Project from Britain would typically have already been
involved in atomic research with the Tube Alloys programme.
83 Pierre, Nuclear Politics, p. 51.

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agreement”, whilst also rejecting the notion that information should be shared
with other parties.85 Sherwin believes that Roosevelt’s acceptance of this
agreement was recognition of Britain’s value as an ally in the post-war world,
and states that “Great Britain would be America’s outpost on the European
frontiers, the sentinel for the New World in the Old.”86 However, unlike
Churchill, the President did not share information on the existence of the Aide-
Memoire with his advisors, choosing instead to give what Paul describes as
the “key to world security and American global power” to a clerk and simply
instructing him to file it away without giving any indication of its importance.87
88 This would cause problems at a later stage, as the authenticity of the British
copy of the document was called into question. Neither Stimson nor Groves
knew about the agreement until after the war, and the fact that the United
States’ copy of the Aide-Memoire was not located until many years later.89
After Roosevelt’s death on the 12th of April 1945, no Americans were aware of
the Aide-Memoire, least of all the new President Harry Truman.
When Germany officially surrendered to the Allies on the 7th of May 1945, full
focus was given to the Manhattan Project and ending the war with Japan. In
April, the Target Committee had been established by Groves in order to
determine which Japanese city best fitted the criteria for bombing, and by its
third meeting the list of targets had been finalised. The targets decided upon
85 Hyde Park Aide-Memoire, NA, PREM 3/139/8A.
86 M. J. Sherwin, A World Destroyed: Hiroshima and the Origins of the Arms Race (New York:
Vintage Books, 1975), pp. 290-1.
88 Given that the Aide-Memoir was titled ‘Tube Alloys’, the clerk in question made the
assumption that it was a naval issue, and as such filed it amongst the files of Roosevelt’s
naval aide.

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were Kokura, Hiroshima, Kyoto, and Niigata.90 Meanwhile, significant
progress had been made in the construction of the atomic bomb, and on the
16th of July the US Army was able to conduct the first ever detonation of an
atomic weapon, codenamed the Trinity Test, on the Alamogordo Bombing and
Gunnery Range in the New Mexican desert. The test was a success, and the
go ahead was given for the bombing of Japan. Upon witnessing the
devastation caused by the explosion, Robert Oppenheimer, the man often
referred to as the ‘father’ of the atomic bomb, famously recalled the following
passage from the Bhagavad Gita, the Hindu scripture:
“Now I am become Death, the destroyer of worlds.”91 92
This quotation is often used in connexion with the Manhattan Project, and
perfectly conveys the astounding destructive power that the Allies now
possessed.93
By the 24th of July, a plan of operation for the atomic bombing of Japan had
been put in place, and on July 26th, the Potsdam Declaration was issued to
Japan. This declaration outlined the terms for their surrender, as had been
agreed at the Potsdam Conference, and warned that if they did not comply,
90 Nagasaki was added to the target list after Stimson insisted on removing Kyoto from it due
to its historical significance. The second atomic bomb was intended for Kokura, but as clouds
obscured it on the 9th of August, it was dropped on Nagasaki, the secondary target.
91 Oppenheimer was appointed to head the Manhattan Project’s secret weapons laboratory
by Groves in September 1942, and was considered one of the key figures in the construction
of the atomic bomb.
92 L. Giovannitti and F. Freed, The Decision to Drop the Bomb (New York: Coward McCann,
1965), p. 197.
93 J. A. Hijiya, ‘The Gita of J. Robert Oppenheimer’, Proceedings of the American
Philosophical Society, 144.2 (2000), pp. 123-4.

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they would be faced with “prompt and utter destruction.”94 When the
Japanese rejected the ultimatum, the decision to drop the bomb was finally
taken, and on the 6th of August the uranium bomb ‘Little Boy’ was dropped on
Hiroshima, and was believed at the time to have killed between seventy and
eighty thousand civilians.95 When Japan still refused to surrender, a plutonium
bomb by the name of ‘Fat Man’ was dropped on Nagasaki on the 9th of
August, leaving “over 35,000 dead and somewhat more than that injured.”96 In
the aftermath of this overwhelming destruction, Japan announced their
surrender on the 15th of August, and by the 2nd of September it had been
formally signed.
On July 26th, the same day that the Potsdam Declaration was made, Clement
Attlee had replaced Winston Churchill as Prime Minister, both Britain and the
United States now had new heads of state. Upon becoming aware of the
atomic bomb project, Attlee perceived it as being an equal project, and wrote
to Truman on the 8th of August expressing a desire that they should issue a
joint statement of their intentions.97
94 ‘Potsdam Declaration: Proclamation Defining Terms for Japanese Surrender, July 26,
1945’, reproduced at <http://www.atomicarchive.com/Docs/Hiroshima/Potsdam.shtml>
[accessed 4 May 2015]
95 ‘U.S. Strategic Bombing Survey: The Effects of the Atomic Bombings of Hiroshima and
Nagasaki’, reproduced at
<http://www.trumanlibrary.org/whistlestop/study_collections/bomb/large/documents/pdfs/65.p
df> [accessed 2 May 2015]
96 ‘U.S. Strategic Bombing Survey: The Effects of the Atomic Bombings of Hiroshima and
Nagasaki’, reproduced at
<http://www.trumanlibrary.org/whistlestop/study_collections/bomb/large/documents/pdfs/65.p
df> [accessed 2 May 2015]
97 F. Williams, A Prime Minister Remembers: The War and Post-War Memoirs of the Rt. Hon.
Earl Attlee (London: William Heinemann, 1961), p. 95.

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By October, both men were in accordance that the atomic weapons that they
possessed should be put under the control of the United Nations, and it was
agreed that they should meet in early November. It was at this meeting on the
15th of November that Truman, Attlee, and the Canadian Prime Minister
Mackenzie King signed the Washington Declaration.98 This declaration
agreed to keep both the CPC and the CDT intact, and encouraged the
creation of a United Nations commission to control the use of atomic energy,
and by January 1946, the United Nations Atomic Energy Commission had
been established, with its main directive of "[dealing] with the problems raised
by the discovery of atomic energy."99 However, private discussions between
the advisors of the British and American governments were taking place on
the same date. These discussions were geared towards the reformulation of
the Quebec Agreement, and “the basic principle of all-round collaboration”
was agreed.100 The parties decided not to draw up a formal agreement that
would have to be submitted to the US Senate, choosing instead to present the
President and the Prime Minister with a brief informal document that
confirmed “full and effective cooperation in the field of atomic energy between
the United States, the United Kingdom and Canada.” This “flimsy piece of
paper”, which was signed by Truman and Attlee in great haste before the
close of their conference, promoted a close three power agreement hoping to
monopolise the raw materials required for atomic energy, and greatly
98 Paul, Nuclear Rivals, pp. 80-3; Baylis, Anglo-American Defence Relations, p. 31.
99 ‘Declaration on Atomic Bomb by President Truman and Prime Ministers Attlee and King’,
reproduced at <http://www.nuclearfiles.org/menu/key-issues/nuclear-energy/history/dec-
truma-atlee-king_1945-11-15.htm> [accessed 1 May 2015]; ‘Establishment of a Commission
to Deal with the Problems Raised by the Discovery of Atomic Energy’, United Nations
General Assembly, January 24, 1946, reproduced at
<http://www.un.org/ga/search/view_doc.asp?symbol=A/RES/1(I)> [accessed 2 May 2015]
100 M. Gowing, Independence and Deterrence: Britain and Atomic Energy, 1945-1952.
Volume 1: Policy Making (London: Macmillan, 1974), p. 75.

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contradicted the Washington Declaration’s lofty ideals of laying aside
nationalist ideas in order to save the save the world.101 Once Truman, having
not fully realised the implications of the document, recognised the
inconsistencies between it and the Washington Declaration, it became
apparent that the Americans did not intend to implement the agreement of full
collaboration with the British.
By April, there had been no progress in terms of collaboration, with the
American representatives of the CPC claiming that a secret agreement was
no longer possible due to the presence of the UNAEC. Byrnes, the US
Secretary of State referred the members of the CPC to article 102 of the UN
Charter, which read as follows:
“Every treaty and every international agreement entered into by any member
of the United Nations after the present Charter comes into force shall as soon
as possible be registered with the Secretariat and published by it.”102
As both nations wished to avoid the ignominy that would surround the
disclosure of any secret agreement, an alternative was needed. Lord Halifax,
who was the British Ambassador to the United States, proposed at a CPC
meeting on the 15th of April that they simply make significant amendments to
the existing Quebec Agreement instead of drawing up a new one.103 However,
both the American and Canadian delegates considered that these
101 Ibid., pp. 76-7.
102 Atomic Energy, December 8, 1945, NA, FO 800/541.
103 Roger Bullen and M. E. Pelly, eds., ‘Prime Minister to Lord Halifax’, March 6, 1946, no. 45,
in Documents on British Policy Overseas, series 1, vol. 4 (London: Her Majesty’s Stationery
Office, 1987)

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amendments would constitute a new agreement, and it was decided that the
matter should be referred back to the heads of state.
This continued lack of agreement from the CPC led Attlee to send a cable to
Truman the following day, in which he expressed that he was “gravely
disturbed” by the fact that Britain was being placed in a position that was
inconsistent with the agreements made in Washington in November. He was
adamant that there should be full and effective cooperation between both
countries, and that he expected the full disclosure of technological and
engineering information, as well as a fair division of the raw materials.104
Truman’s response came swiftly, on the 20th of April, and argued that the
agreement that stood between them referred only to cooperation in “the field
of basic scientific research”, rather than an obligation to furnish the
engineering and operational assistance required for another atomic energy
plant. He then went on to state that the full and effective cooperation that
Attlee had referred to was only applicable in the field of basic scientific
research, and nothing more.105 By making this statement, Truman was
denying the meaning of the words ‘full and effective cooperation’ by virtue of a
technicality, and utilised the nuances of diplomatic language to such an extent
that the Canadians dubbing his telegram to Attlee as a ‘solicitor’s letter’.106 By
the time Attlee sent a response voicing his displeasure at Truman’s seeming
abandonment of the “special relationship” that had been developed in the field
of atomic energy during the war, the McMahon Act was passing through
104 Bullen and Pelly, ‘Prime Minister to Lord Halifax’
105 U.S. Department of State, ‘President Truman to Mr. Attlee’, April 20, 1946, in Foreign
Relations of the United States: General; the United Nations, 1946, vol. 1, pp. 1235-7.
106 Gowing, Independence and Deterrence. Vol. 1, p. 101.

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Congress, and Truman had decided against any further exchanges of
information.107
The Atomic Energy Act of 1946, or the McMahon Act, came into law on
August the 1st, 1946, and determined how the United States would control
and manage the nuclear technology it had jointly developed with its wartime
allies. It also established the United States Atomic Energy Commission, which
would take over nuclear development from the Army.108 David Reynolds
describes the McMahon Act as being the result of “a nationalistic, secrecy-
conscious Congress, anxious that the United States alone should control the
‘superbomb’.”109 By passing this act, which prohibited the exchange of any
atomic information to a foreign government, the Americans had shut down
any further possibility of collaboration between themselves and the British.
Following the dissolution of the atomic relationship with the United States as a
result of the McMahon Act, Britain decided in January 1947 to go ahead with
an independent program to develop an atomic bomb. However, Gowing
believes that the decision to go ahead with the project was more down to
Britain’s desire to continue being considered a great power than it was a
direct response to the McMahon Act. While it is certainly true that Britain
would inevitably have undertaken an atomic bomb project at some point, it
would not necessarily have done so independently. The McMahon Act acted
107 Baylis, Anglo-American Defence Relations, p. 33.
108 Atomic Energy Act Of 1946 (Public Law 585, 79th Congress), reproduced at
<https://www.osti.gov/atomicenergyact.pdf> [accessed 1 May 2015]
109 D. Reynolds, From World War to Cold War: Churchill, Roosevelt, and the International
History of the 1940s (Oxford: Oxford University Press, 2007), p. 321.

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as a catalyst for British bomb production, just as the MAUD report had done
for American atomic research.
Despite the seeming finality of the McMahon Act, Britain was eager to be in a
position to renew the Anglo-American collaborative relationship if the
opportunity arose. By undertaking the independent manufacture of an atomic
bomb, they would put themselves in a strong position to be able to resume
cooperation.110 Additionally, Ernest Bevin, the British Foreign Secretary
believed that possessing its own atomic capabilities would provide Britain with
an increased influence in foreign affairs, and re-establish its identity as a great
power.111 As the MAUD report had stated, complete disarmament would be
the only event in which the production of an atomic bomb could be deemed a
waste, as “no nation would care to risk being caught without a weapon of such
decisive possibilities”, especially in the increasingly hostile post-war
climate.112
When the United States showed interest in reopening talks on atomic matters
with Britain in late 1947, the prospect of a renewed collaboration looked fairly
good. At a CPC meeting on the 7th of January 1948, an agreement known as
the Modus Vivendi was concluded. In order to circumvent Article 102 of the
UN Charter, the document was not signed, with both sides instead agreeing to
adhere to its terms.113 The Modus Vivendi agreement provided that; all
110 Gowing, Independence and Deterrence. Vol. 1, p. 115; Baylis, Anglo-American Defence
Relations, p. 33.
111 I. Clark and N. J. Wheeler, The British Origins of Nuclear Strategy, 1945-55 (Oxford:
Clarendon Press, 1989), pp. 43-51.
112 Report of M.A.U.D. Committee, NA, AB 1/238.
113 Baylis, Anglo-American Defence Relations, p. 42.

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wartime agreements not related to raw materials became void, the United
States no longer required British ‘consent’ before using the bomb, all of the
uranium produced in the Congo was allocated to the US between 1948 and
1949, that atomic information would be exchanged in mutually agreed areas,
and that the US would be provided with raw materials from the British
stockpile if they needed it.114 This agreement gave the Americans legislative
control over their usage of their atomic weapons, while the British gained
access to the atomic information that they required for their own bomb project.
Although Cockcroft described the Modus Vivendi as a new beginning, a first
step in post-war atomic collaboration, it also signalled the final step in wartime
atomic collaboration.115 While the secret agreements of the war still stood, any
atomic relationship between the United States and Great Britain would be
inherently tied to the Manhattan Project and their combined efforts on it. By
signalling the beginning of a new atomic era, it simultaneously marked the
end of the first atomic era.
114 ‘Minutes of Combined Policy Committee’, January 7, 1948, in Foreign Relations of the
United States: General; the United Nations, 1948, vol. 1, pt. 2 (Washington D.C.: Government
Printing Office, 1973), pp. 679-86: “Modus Vivendi” of 1948: accord between UK, US and
Canada on cooperation in field of atomic energy, NA, PREM 11/786.
115 G. Hartcup and T. E. Allibone, Cockcroft and the Atom (Bristol: Adam Hilger, 1984), p.
221.

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Conclusion
British contributions to the Manhattan Project from the Quebec Agreement
onwards can best be described as helpful, but not vital. By the time that they
were fully introduced to the work, American research had significantly
surpassed that of their own. They were unable to have as big an impact on
the project as they would have liked, but was this indicative of their role in the
wider context of the decade?
When assessing the balance of atomic cooperation between Britain and the
United States, the insight of General Leslie Groves is a useful one. As the
central figure in the central organisation of the collaborative relationship
between 1940 and 1948, he is extremely well placed to comment. While he
witnessed first hand their struggle to significantly impact the development of
the atomic bomb, Groves “cannot escape the feeling that without active and
continuing British interest there probably would have been no atomic bomb to
drop on Hiroshima.”116 Almost begrudgingly, he praises their determination to
ensure that the work was completed by any means necessary, and applauds
the fact that they recognised that they could accomplish their purpose through
the United States. The British started off with the intention of completing the
project independently, before seeking collaboration once it became evident
that they could not complete it by themselves. The Americans on the other
hand, paid no real attention to the atomic bomb project until the British
research team had done all of the hard preliminary work. Admittedly, the

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peaking of their interest also coincided with the Japanese bombing of Pearl
Harbor and the United States’ subsequent entry into the war, but they had
already began indicating that they would be in favour of a collaboration of
some sorts.
In his 1962 account, titled Now It Can Be Told: The Story of the Manhattan
Project, Groves describes a “chance meeting between a Belgian and an
Englishman” in May 1939 which could well have been directly responsible for
the success of the Allied atomic program over that of the Axis powers. The
Englishman in question was Henry Tizard, at the time the director of the
Imperial College of Science and Technology, while the Belgian was M. Edgar
Sengier, the managing director of Union Minière du Haut Katanga, a Belgian
mining company. After unsuccessfully attempting to convince Sengier to grant
the British Government an option on all of the radium-uranium ore extracted
from the Shinkolobwe Mine in the Belgian Congo, Tizard took him by the arm
and said to him:
“Be careful, and never forget that you have in your hands something which
may mean a catastrophe to your country and mine if this material were to fall
into the hands of a powerful enemy.”117
Tizard’s portentous statement, coupled with his status as a renowned scientist
made a lasting impression on Sengier, and made him recognize the strategic
value of the ore that resided in the mine. When war broke out a few months

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after his encounter with Tizard, he ordered that all of Union Minière’s available
radium be sent to Great Britain and the United States, and towards the end of
1940 he directed the shipment of all of the Shinkolobwe mine’s uranium ore to
the United States. The materials transported included about 120 grams of
radium, and over 1,250 tons of uranium ore.
Sengier’s importance to the Allied cause is unquestionable, and therefore the
lasting impression made on him by Henry Tizard’s warning in 1939 can be
considered a critical part of the Manhattan Project’s success. Without their
meeting, it is entirely possible that Sengier would have remained oblivious to
the strategic importance of the resources that he possessed, and that the
Germans could have gained access to them. Had they obtained these vast
quantities of uranium ore before the Allies did, it is certainly possible, if not
probable that their atomic bomb project would have succeeded first.
This intervention by Tizard is further evidence of the important role that the
British played in the collaborative relationship. Although it is not an example of
atomic research that formed the foundation for the Manhattan Project, it is
nonetheless an additional case of Britain making life easier for the United
States. By planting the seed in Sengier’s mind, Tizard helped create the ideal
conditions for the pursuit of a large-scale atomic programme, just as various
scientific discoveries did.
Without the initial research undertaken by Britain in the early 1940s it is
extremely doubtful that the Manhattan Project would have succeeded within

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the timeframe of the war, if at all. Admittedly, Britain would not have been able
to complete their own project without American assistance, but as they were
the lesser power that is to be expected. That the United States, on the other
hand, was unable to succeed without the preliminary work of the British
programme, is altogether more remarkable.

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