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Discovery of Nuclear Fission
Otto Hahn and Fritz Strassman discover nuclear fission in uranium. They learned that the splitting atom releases a huge amount energy. -
Einstein-Szilard Letter
Both Leo Szilard and Albert Einstein write a letter to U.S. President Franklin D. Roosevelt, warning them that Nazi German might be developing atomic weapons. Urging the U.S. to begin similiar research. -
Formation of the Manhattan Project
Formation of the Manhattan Project- In response to the letter the U.S. establishes the Manhattan Project, a top secret research project about the development of the atom bomb. -
The First Controlled Nuclear Chain Reaction
On Dec. 2, 1942 scientists at the University of Chicago achieve the first controlled nuclear chain reaction. -
Development of the Atomic Bomb
1943-1945 The Manhattan Project is directed by J. Robert Oppenheimer. During this time the U.S. Government works on the design of the bomb, including both uranium-235 and plutonium-239 -
The Trinity Test
The first successful test of an atomic bomb takes place in Los Alamos, New Mexico. This marks the first time a nuclear fission weapon is unleashed. -
Hiroshima
The U.S. drops the first atomic bomb, "Little Boy" on the Japanese city of Hiroshima killing between 70,000-80,000 people. -
Nagasaki
Three days after Hiroshima, the U.S. drops the second atomic bomb, "Fat Man" on Nagasaki killing between 40,000-75,000 people. -
Japan Surrenders
Japan surrenders effectively ending World War II. This was after the Hiroshima and Nagasaki bombing.