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German scientists learn how to split a uranium atom
German physicits learn how to split a uranium atom, causing fears that they may create an atomic bomb. -
Einstein's letter to Franklin D. Roosevelt
Leo Szilard and Eugene Wigner drafted a letter to President Franklin D. Roosevelt that was signed by Albert Einsteain, urging the U.S. to accelerate nuclear research and obtain large stores of uranium. They were worried that Nazi scientists could create an atomic bomb before the U.S. did, which would be a disaster. This letter started the U.S. nuclear program, and without it the atom bomb probably would not have happened. -
Advisory Commitee on Uranium meeting
A meeting was held between Lyman Briggs, Szilard, Wigner, and Edward Teller helt a meeting to evaluate the concerns of the letter. They determined that uranium could produce a bomb vastly stronger than any other bombs. This confirmed that an atom bomb could be made -
Executive Order 8807
President Roosevelt signed executive order 8807, electing Vannevar Bush as the director of the newly formed Office of Scientific Research and Development. This office researched and developed uranium. -
President approved the atomic program
The U.S. atomic program was approved, and there was also a Top Policy Group to control it consisting of top politicians and military officals. This projet was led by the army, not the navy. -
WAR!
The U.S declares war on Germany and Italy -
The Manhattan Engineering District is established
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Robert Oppenheimer appointed coordinator of the project at the Sity Y Laboratory
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The first nuclear reactor goes critical
Chicago Pile-1, at the University of Chicago, goes critical under the leadership of Enrico Fermi -
The world's first nuclear explosion
The Trinity nuclear test of an implosion-style nuclear bomb is exploded at Alamogordo, New Mexico. Many of the scientists developing the bomb begin to have doubts about what they have created. -
Atomic Bomb approved for use
President Truman approved atomib bomb to be used on Japan, on one of four cities. -
Little Boy dopped over Japan
The uranium bomb Little Boy is detonated over Hiroshima, Japan, killing over 100,000 people. -
Fat Man dropped over Japan
The second atomic bomb was dropped over Nagasaki, Japan. -
Oppenhemier refuses to develop a hydrogen bomb
Oppenhemier refused to develop the Hydrogen Bomb, not wanting to cause any more destruction.