Atom Bomb Timeline By km18434 Feb 1, 1931 Heavy hydrogen or deuterium is discovered by Harold C. Urey. Feb 25, 1932 The atom is split by John Crockcroft Feb 25, 1933 Leo Szilard realizes the possibility of the nuclear chain reaction Feb 25, 1934 The first nulcear fission is achieved by Enrico Fermi of Italy. Jan 29, 1939 Niels Bohr announces the discovery of fission Jan 29, 1939 Robert Oppenheimer realizes the military possibilities of nuclear fission. Aug 2, 1939 Albert Einstein writes to President about the use of Uranium as a new source of energy. Sep 1, 1939 World War II begins Feb 23, 1941 Plutonium is discovered by Glenn Seaborg. Oct 9, 1941 FDR gives the go-ahead for the develpment of the atomic weapon Dec 6, 1941 FDR authorizes the Manhattan Engineering District for the purpose of creating an atomic bomb. This would later be called the 'Manhattan Project'. Sep 23, 1942 Colonel Leslie Groves is placed in charge of the Manhattan Project. J. Robert Oppenheimer becomes the Project's Scientific Director. Dec 2, 1942 First controlled nuclear fussion reaction is produced by Enrico Fermi at the University of Chicago May 5, 1943 Japan becomes primary target for future atomic bomb Apr 27, 1945 Target committee of the project select four cities as targets for the atomic bomb. Cities: Kyoto, Hiroshima, Kokura, and Niigata. Jul 16, 1945 The world's first atomic detonation takes place in the 'Trinity Test' at Alamogordo, New Mexico. Jul 21, 1945 President Truman orders atomic bombs to be used. Sep 2, 1945 Japan announces its formal surrender. Oct 13, 1945 Edward Teller tries to help build a new hydrogen bomb.