American physicist J. Robert Oppenheimer headed the Manhattan Project to develop atomic bombs for the United States, and Edward Teller was among the first scientists recruited for the project. Leo Szilard and Enrico Fermi built the first nuclear reactor. Ernest Orlando Lawrence was program chief in charge of the development of the electromagnetic process of separating uranium-235. The person who oversaw the project, however, was not a scientist. He was U.S. Army Brigadier General Leslie R. Groves. In all, more than one hundred thousand people were employed for the Manhattan Project. The bombings themselves were carried out by the pilot of the Enola Gay Colonel Paul Warfield Tibbets, Jr., and pilot of the Bockscar Major Charles W. Sweeney and their respective crews.
atomic bombings of Hiroshima and Nagasaki Article