page_title: High Explosive Research
section_title: Manhattan Project
hierarchical_section_title: High Explosive Research / Background / Manhattan Project
caption_attribution_description: English: James Chadwick (left) with Major General Leslie R. Groves, Jr.
context_page_description: High Explosive Research was the British project to develop atomic bombs independently after the Second World War. This decision was taken by a cabinet sub-committee on 8 January 1947, in response to apprehension of an American return to isolationism, fears that Britain might lose its great power status, and the actions by the United States to withdraw unilaterally from sharing of nuclear technology under the 1943 Quebec Agreement. The decision was publicly announced in the House of Commons on 12 May 1948.
  HER was a civil project, not a military one. Staff were drawn from and recruited into the Civil Service, and were paid Civil Service salaries. It was headed by Lord Portal, as Controller of Production, Atomic Energy, in the Ministry of Supply. An Atomic Energy Research Establishment was located at a former airfield, Harwell, in Berkshire, under the direction of John Cockcroft. The first nuclear reactor in the UK, a small research reactor known as GLEEP, went critical at Harwell on 15 August 1947. British staff at the Montreal Laboratory designed a larger reactor, known as BEPO, which went critical on 5 July 1948.
context_section_description: In July 1940, Britain had offered to give the United States access to its scientific research, and Cockcroft, as part of the Tizard Mission, briefed American scientists on British developments. He discovered that the American project was smaller than the British, and not as far advanced. The British and American projects exchanged information, but did not initially combine their efforts. British officials did not reply to an August 1941 American offer to create a combined project. In November 1941, Frederick L. Hovde, the head of the London liaison office of the American Office of Scientific Research and Development (OSRD), raised the issue of cooperation and exchange of information with Anderson and Lord Cherwell, who demurred, ostensibly over concerns about American security. Ironically, it was the British project that had already been penetrated by atomic spies for the Soviet Union.
  The United Kingdom did not have the manpower or resources of the United States, and despite its early and promising start, Tube Alloys fell behind its American counterpart and was dwarfed by it. On 30 July 1942, Anderson advised the Prime Minister, Winston Churchill, that: "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."
  The British considered producing an atomic bomb without American help, but the project would have needed overwhelming priority, the projected cost was staggering, disruption to other wartime projects was inevitable, and it was unlikely to be ready in time to affect the outcome of the war in Europe. The unanimous response was that before embarking on this, another effort should be made to secure American cooperation. At the Quadrant Conference in August 1943, Churchill and the American President, Franklin Roosevelt, signed the Quebec Agreement, which merged the two national projects. Its terms made it clear that Britain was the junior partner in the Grand Alliance. The British considered the Quebec Agreement to be the best deal they could have struck under the circumstances, and the restrictions were the price they had to pay to obtain the technical information needed for a successful post-war nuclear weapons project. Margaret Gowing noted that the "idea of the independent deterrent was already well entrenched."
  The Quebec Agreement established the Combined Policy Committee and the Combined Development Trust to coordinate their efforts. The 19 September 1944 Hyde Park Aide-Mémoire extended both commercial and military cooperation into the post-war period. A British mission led by Akers assisted in the development of gaseous diffusion technology at the SAM Laboratories in New York. Another, led by Oliphant, who acted as deputy director at the Berkeley Radiation Laboratory, assisted with the electromagnetic separation process. Cockcroft became the director of the Anglo-Canadian Montreal Laboratory. The British mission to the Los Alamos Laboratory led by James Chadwick, and later Peierls, included distinguished scientists such as Geoffrey Taylor, James Tuck, Niels Bohr, William Penney, Frisch, Ernest Titterton and Klaus Fuchs, who was later revealed to be a Soviet spy. As overall head of the British Mission, Chadwick forged a close and successful partnership with Brigadier General Leslie R. Groves, the director of the Manhattan Project. He ensured that British participation was complete and wholehearted.
caption: James Chadwick (left), head of the British Mission, with Major General Leslie R. Groves, Jr., director of the Manhattan Project
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