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Manhattan Project

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The Manhattan Project was the program based in the United States which tried to make the first nuclear weapons. The project went on during World War II, and was run by the U.S. Army. The head of the project was General Leslie R. Groves, who had led the building of the Pentagon. The top scientist on the project was Robert Oppenheimer, a famous physicist. The project cost $2 billion, and created many secret cities and bomb-making factories, such as a laboratory in Los Alamos, New Mexico, a nuclear reactor in Hanford, Washington, and a uranium processing plant in Oak Ridge, Tennessee.

The Manhattan Project had to find solutions to two difficulties. The first difficulty is how to make the special isotopes of uranium (uranium-235) or plutonium. This process is called separation and is very slow. The United States built very big buildings with three different kinds of machine for separation. They made enough fissionable special isotopes for a few nuclear weapons. The second difficulty was how to make a bomb that will produce a big nuclear explosion every time. A weapon with a bad design can make a much smaller nuclear explosion. This is called a "fizzle". In July 1945, the Manhattan Project solved the two difficulties and made the first nuclear explosion. This test of a nuclear weapon was called "Trinity" and was a success.

The Manhattan Project created two nuclear bombs which the United States used against Japan in 1945.


Uncle Sam has removed his hat and is rolling up his sleeves. On the wall in front of him are three monkeys and the slogan: What you see here / What you do here / What you hear here / When you leave here / Let it stay here.
A billboard encouraging secrecy among Oak Ridge workers

The Manhattan Project operated under a blanket of tight security. This was to prevent the Axis countries, especially Nazi Germany, from accelerating their own nuclear projects or undertaking covert operations against the project.[1] The possibility of sabotage was always present. At times, people suspected sabotage when equipment failed. While there were some problems believed to be the result of careless or disgruntled employees, there were no confirmed instances of Axis-instigated sabotage.[2] However, on 10 March 1945, a Japanese fire balloon struck a power line, and the resulting power surge caused the three reactors at Hanford to be temporarily shut down.[3]

Maintaining security was difficult because so many people worked on the project. A special Counter Intelligence Corps detachment handled the project's security issues.[4] By 1943, it was clear that the Soviet Union was trying to penetrate the project. Lieutenant Colonel Boris T. Pash, the head of the Counter Intelligence Branch of the Western Defense Command, investigated suspected Soviet espionage at the Radiation Laboratory in Berkeley. Oppenheimer informed Pash that he had been approached by a fellow professor at Berkeley, Haakon Chevalier, about passing information to the Soviet Union.[5]

The most successful Soviet spy was Klaus Fuchs. Fuchs was a member of the British Mission who played an important part at Los Alamos.[6] The 1950 revelation of Fuchs' espionage activities damaged the United States' nuclear cooperation with Britain and Canada.[7] Subsequently, other instances of espionage were uncovered, leading to the arrest of Harry Gold, David Greenglass and Ethel and Julius Rosenberg.[8] Other spies like George Koval remained unknown for decades.[9] People will never know the value of the espionage. One reason was that the Soviet atomic bomb project was held back by a shortage of uranium ore. The consensus is that espionage saved the Soviets one or two years of effort.[10]


  1. Jones 1985, pp. 253–255
  2. Jones 1985, pp. 263–264.
  3. Jones 1985, p. 267
  4. Jones 1985, pp. 258–260
  5. Jones 1985, pp. 261–265
  6. Groves 1962, pp. 142–145.
  7. Hewlett & Duncan 1969, pp. 312–314.
  8. Hewlett & Duncan 1969, p. 472.
  9. Broad, William J. (12 November 2007). A Spy’s Path: Iowa to A-Bomb to Kremlin Honor. pp. 1–2. Retrieved 2 July 2011. 
  10. Holloway 1994, pp. 222–223.

Further reading

General, administrative, and diplomatic histories
  • Bernstein, Barton J. (June 1976). "The Uneasy Alliance: Roosevelt, Churchill, and the Atomic Bomb, 1940–1945". The Western Political Quarterly (University of Utah) 29 (2): 202–230. 
  • Fine, Lenore; Remington, Jesse A. (1972). The Corps of Engineers: Construction in the United States. Washington, D.C.: United States Army Center of Military History. OCLC 834187
  • Frisch, David H. (June 1970). "Scientists and the Decision to Bomb Japan". Bulletin of the Atomic Scientists (Educational Foundation for Nuclear Science) 26 (6): pp. 107–115. 
  • Gilbert, Keith V. (1969). History of the Dayton Project. Miamisburg, Ohio: Mound Laboratory, Atomic Energy Commission. OCLC 650540359
      . Retrieved 21 July 2011. 
  • Gosling, Francis George (1994). The Manhattan Project : Making the Atomic Bomb. Washington, DC: United States Department of Energy, History Division. OCLC 637052193
      . OCLC 637004643
  • Hewlett, Richard G.; Duncan, Francis (1969). Atomic Shield, 1947–1952. A History of the United States Atomic Energy Commission. University Park: Pennsylvania State University Press. ISBN 0-520-07187-5
      . OCLC 3717478
  • Holloway, David (1994). Stalin and the Bomb: The Soviet Union and Atomic Energy, 1939–1956. New Haven, Connecticut: Yale University Press. ISBN 0-300-06056-4
      . OCLC 29911222
  • Howes, Ruth H.; Herzenberg, Caroline L. (1999). Their Day in the Sun: Women of the Manhattan Project. Philadelphia: Temple University Press. ISBN 1-56639-719-7
      . OCLC 49569088
  • Hunner, Jon (2004). Inventing Los Alamos: The Growth of an Atomic Community. Norman: University of Oklahoma Press. ISBN 978-0-8061-3891-6
      . OCLC 154690200
  • Johnson, Charles; Jackson, Charles (1981). City Behind a Fence: Oak Ridge, Tennessee, 1942–1946. Knoxville: University of Tennessee Press. ISBN 0-87049-303-5
      . OCLC 6331350
  • Jones, Vincent (1985). Manhattan: The Army and the Atomic Bomb. Washington, D.C.: United States Army Center of Military History. OCLC 10913875
      . OCLC 13793436
Technical histories
  • Ahnfeldt, Arnold Lorentz, ed. (1966). Radiology in World War II. Washington, D.C.: Office of the Surgeon General, Department of the Army. OCLC 630225
  • Hansen, Chuck (1995a). Volume I: The Development of US Nuclear Weapons. Swords of Armageddon: US Nuclear Weapons Development since 1945. Sunnyvale, California: Chukelea Publications. ISBN 978-0-9791915-1-0
      . OCLC 231585284
  • Hansen, Chuck (1995b). Volume V: US Nuclear Weapons Histories. Swords of Armageddon: US Nuclear Weapons Development since 1945. Sunnyvale, California: Chukelea Publications. ISBN 978-0-9791915-0-3
      . OCLC 231585284
  • Hoddeson, Lillian; Henriksen, Paul W.; Meade, Roger A.; Westfall, Catherine L. (1993). Critical Assembly: A Technical History of Los Alamos During the Oppenheimer Years, 1943–1945. New York: Cambridge University Press. ISBN 0-521-44132-3
      . OCLC 26764320
      . OCLC 23693470
      .  (Available on Wikimedia Commons)
  • Thayer, Harry (1996). Management of the Hanford Engineer Works In World War II: How the Corps, DuPont and the Metallurgical Laboratory Fast Tracked the Original Plutonium Works. New York: American Society of Civil Engineers Press. ISBN 0-7844-0160-8
      . OCLC 34323402
Participant accounts
      . OCLC 22661282
      . OCLC 8805725
      . OCLC 537684
      . OCLC 4665032
      . OCLC 15223648
      . OCLC 1528346

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