page_title: British hydrogen bomb programme
section_title: Manhattan Project
hierarchical_section_title: British hydrogen bomb programme / Background / Manhattan Project
caption_attribution_description: Scientific advisories consult with Major General Leslie R. Groves, Officer in Charge of Manhattan Engineer District.
context_page_description: The British hydrogen bomb programme was the ultimately successful British effort to develop hydrogen bombs between 1952 and 1958.
  During the early part of the Second World War, Britain had a nuclear weapons project, codenamed Tube Alloys. At the Quebec Conference in August 1943, British prime minister Winston Churchill and United States president Franklin Roosevelt signed the Quebec Agreement, merging Tube Alloys into the American Manhattan Project, in which many of Britain's top scientists participated. The British government trusted that America would share nuclear technology, which it considered to be a joint discovery, but the United States Atomic Energy Act of 1946 ended technical cooperation.
  Fearing a resurgence of American isolationism, and the loss of Britain's great power status, the British government resumed its own development effort, which was codenamed "High Explosive Research".
  The successful nuclear test of a British atomic bomb in Operation Hurricane in October 1952 represented an extraordinary scientific and technological achievement.
context_section_description: In July 1940, Britain offered the United States access to its scientific research, and Cockcroft briefed American scientists on British nuclear weapons developments. He discovered that the American S-1 Project (later renamed the Manhattan Project) was smaller than the British, and not as far advanced. The two projects exchanged information, but did not initially combine their efforts, 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. The British considered producing an atomic bomb without American help, but it would require overwhelming priority, 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. At the Quebec Conference in August 1943, the Prime Minister, Winston Churchill, and the President of the United States, Franklin Roosevelt, signed the Quebec Agreement, which merged the two national projects. The Quebec Agreement established the Combined Policy Committee and the Combined Development Trust to coordinate their efforts. The 19 September 1944 Hyde Park Agreement 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, headed by Mark Oliphant, assisted with the electromagnetic separation process at the Berkeley Radiation Laboratory. Cockcroft became the director of the joint British-Canadian Montreal Laboratory. A British mission to the Los Alamos Laboratory was led by Chadwick, and later Peierls, which included several of Britain's most eminent scientists. As overall head of the British Mission, Chadwick forged a close and successful partnership, and ensured that British participation was complete and wholehearted.
caption: James Chadwick (left), the head of the British Mission, with Major General Leslie R. Groves Jr., the director of the Manhattan Project; Richard C. Tolman, his scientific advisor; and Henry DeWolf Smyth
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