Manhattan Project

The Manhattan Project was the U.S. project conducted during World War II to develop a nuclear weapon. It was commanded by Major General Leslie Groves, with J. Robert Oppenheimer as technical director. Set up in 1942, the project came to a head with the detonation of the first fission device, the Trinity test, in 1945 at White Sands, New Mexico.

The project then built the Little Boy used at Hiroshima and the Fat Man bombs used on Nagasaki, on, respectively, August 6 and August 9, 1945.

See also: Los Alamos National Laboratory and Nuclear attacks against Japan for more details.

Major facilities included:

• "Site Y" in New Mexico, the actual bomb laboratory, now the Los Alamos National Laboratory
• Gaseous diffusion plant for uranium in Tennessee, now the Oak Ridge National Laboratory
• Hanford Plant, in Washington (U.S. state), now closed but the major plutonium production facility
• "Metallurgical Laboratory" at the University of Chicago, the first nuclear reactor