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Enrico Fermi of Italy irradiates uranium with neutrons. He believes he has produced the first transuranic element, but unknowingly achieves the world's first nuclear fission.
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Einstein and several other scientists told Roosevelt of efforts in Nazi Germany to purify uranium-235, which could be used to build an atomic bomb.
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The day before the bombing of Pearl Harbor, President Roosevelt authorizes the Manhattan Engineering District with $2 billion to build the atom bomb.
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At the University of Chicago, in a squash court under Stagg Field, Enrico Fermi and his team produce the world's first controlled and self-sustained nuclear fission reaction.
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Colonel Leslie Groves is promoted to Brigadier-General and put in charge of the Manhattan Project. He recruits J. Robert Oppenheimer as Scientific Director.
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The US Military begin remodeling the B-29 bomber for the delivery of the A-bomb. Bomb's sizes are decided: "Thin Man" representing Roosevelt and "Fat Boy" for Churchill.
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Important military port in the San Francisco Bay goes up in a horrific explosion killing 323 men, disintegrating two ships and an entire train. Calculations and declassified documents lead to a possible US test firing of a nuclear weapon.
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Little Boy explodes over Hiroshima killing over 100,000 people. Three days later, Fat Man explodes over Nagasaki killing 75,000. Japan surrenders soon after.