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The Army Corps of Engineers establishes the Manhattan Engineer District to develop and build the atomic bomb. Uranium isotope separation facilities are built at Oak Ridge, Tennessee; plutonium production reactors are built at Hanford, Washington; and a weapons laboratory is set up at Los Alamos, New Mexico.
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President Roosevelt dies. Harry S. Truman becomes President.
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The gun model uranium bomb, called Little Boy, is dropped on Hiroshima, Japan.
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The implosion model plutonium bomb, called Fat Man, is dropped on Nagasaki, Japan. Five days later, Japan surrenders.
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President Truman signs the Atomic Energy Act of 1946 transferring Manhattan Project assets and responsibilities to the civilian Atomic Energy Commission.
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Soviet Union begins blockade of West Berlin.
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North Korea invades South Korea. The Korean War begins.