History of atomic force

1919: June-Rutherford creates oxygen from nitrogen.
1920: Rutherford speculates on the existence of the neutron at the Royal Society.
1931: November-Urey discovers deuterium.
1932: February-Chadwick discovers the neutron.
1933: April-Born, Courant, Franck and many other scientists are compelled to leave the University of Göttingen because of their "Jewish physics"
October-Szilard recollects that "It occurred to me in October, 1933 that a chain reaction might be set up if an element could be found that would emit two neutrons when it swallowed one neutron."This idea became a classified British patent in 1935 before the fission was discovered.
1934: Artificial radioactivity discovered by Curie/Joliot (bombardment with alpha particles) and by Fermi (bombardment with neutrons).
1938: December-Fermi receives the Nobel prize for the discovery of transuranic elements (actually fission of uranium) and departs for the "new world"
December 22, Hahn and Strassmann (later Meiter and Frisch) conclude that the identification of barium implies that the uranium nucleus has been fissioned by neutrons.
1939: January to May-Many experiments on uranium fission.
August 2-Szilard, Wigner, and Teller obtain a letter from Einstein on the possibility of a uranium weapon; Roosevelt receives the letter on October 11, 1939 from Sachs.
1940: June 3-German scientists fail to observe neutron multiplication in the reactor in Hamburg.
1941: January-Based on experiments with a natural uranium reactor, the Germans reject graphite as a moderator.
July-British 'Maud' Committee reports that a weapon could be made with 10 kg of U-235; U.S. Academy of Sciences endorses bomb program.
1942: May-Heisenberg and Dopel observe the first multiplication of neutrons.
December 2-First nuclear chain reaction at Chicago's Stagg Field by Fermi.
1943: March 15-Oppenheimer moves the bomb development to Los Alamos.
1944: August 26-Bohr presents his memorandum on intentional control of nuclear weapons to Roosevelt.
November-First batch of spent fuel obtained from Hanford reactors.
November-Goudsmit's ALSOS mission obtains documents which imply that the German's rate of progress toward a bomb had diminished.
1945: January- First Pu reprocessing production run at Hanford
January 20- First U-235 separated at Oak Ridge.
June 11- The Franck Report was sent to the Secretary of War.
July 16-U.S. explodes first atomic bomb, the Trinity test, at Alamogordo.
August 6,9-Atomic bombs dropped on Hiroshima and Nagasaki.