The Manhattan Project is the name of the top secret project undertaken by the US during World War 2 to create the world’s first nuclear bomb. The US first approved attempts at isotope separation to enrich uranium in 1940. At the time of its completion of the first nuclear bomb, the program employed 120,000 Americans, only dozens of whom knew of the project’s existence. The project resulted in the only two uses of nuclear bombs in war, when the US dropped them on Hiroshima and Nagasaki. Each detonation killed roughly 70,000 people with around 100,000 additional people dying from radiation. However, many argue the death toll would have been closer to 1,000,000 people if the US was forced to invade mainland Japan, something we likely would have done without the bomb.
Source 1: http://www.ushistory.org/us/51f.asp
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