Original U.S. Department of Energy SealU.S. Department of Energy Office of History and Heritage Resources The Manhattan Project
An Interactive History



1890s-1939: Atomic Discoveries ] 1939-1942: Early Government Support ] [ 1942: Difficult Choices ] 1942-1944: The Uranium Path to the Bomb ] 1942-1944: The Plutonium Path to the Bomb ] 1942-1945: Bringing It All Together ] 1945: Dawn of the Atomic Era ] 1945-present: Postscript -- The Nuclear Age ]

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More Uranium Research, 1942
More Piles and Plutonium, 1942
Enter the Army, 1942
Groves and the MED, 1942
Picking Horses, November 1942
Final Approval to Build the Bomb, December 1942

 

DIFFICULT CHOICES
(1942)
Events

By early 1942, as the United States suffered a series of military defeats in the Pacific, top officials in Washington tentatively had decided to proceed with the construction of an atomic bomb.  Two paths seemed possible.  A uranium bomb could be achieved if sufficient uranium-235 could be produced by one orMet Lab alumni pose at the University of Chicago, December 2, 1946. more of the three isotope separation methods under consideration: gaseous diffusion, centrifuge, and electromagnetic.  A plutonium bomb might provide a quicker route, but it required demonstration that plutonium could be produced in a uranium pile and then be separated in usable quantities.  To this end, Arthur Compton consolidated most plutonium research at the new Metallurgical Laboratory (Met Lab) at the University of Chicago.

A program review conducted in May 1942 determined that no front runner in the race for the bomb existed and recommended that the three isotope separation methods and the pile project be pushed as fast as possible to full production planning.  Construction and security needs suggested placing the program in the Army Corps of Engineers.  In August, the Corps set up the Manhattan Engineer District (MED) to manage the project.  A month later, Colonel Leslie R. Groves was promoted to brigadier general and appointed to head the effort. Leslie Groves, Commanding General of the Manhattan Engineer District Groves moved quickly to narrow the field and move the project along, selecting a site in east Tennessee (Oak Ridge) for the construction of production plants, dropping the centrifuge process from consideration, and choosing J. Robert Oppenheimer to head the bomb research and design laboratory to be built at Los Alamos, New Mexico.  In December, President Franklin Roosevelt gave his final authorization to proceed with construction of the atomic bomb.  

To learn more about any of these difficult choices that had to be made in 1942, choose a web page from the menu below.  To continue with a quick overview of the Manhattan Project, jump ahead to the description of the "Uranium Path to the Bomb, 1942-1944."  

More Uranium Research, 1942
More Piles and Plutonium, 1942
Enter the Army, 1942
Groves and the MED, 1942
Picking Horses, November 1942
Final Approval to Build the Bomb, December 1942

 

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