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The Manhattan Project

In 1942, fearing that Nazi Germany would soon develop an atomic weapon utilizing uranium fission, the United States formed the Manhattan Project with the goal of producing the first nuclear weapon. The Manhattan Project established research and production facilities in three locations across the United States: Hanford, Washington produced weapons-grade plutonium, Oak Ridge, Tennessee, produced uranium-235, and Los Alamos, New Mexico assembled the final nuclear weapons. The project employed over 120,000 personnel, with heavy compartmentalization designed to prevent all but a few key personnel from understanding the full scope of their work. This secrecy allowed the creation of the first nuclear weapon without arousing suspicion from the Axis Powers.

On July 16, 1945, the detonation of the world’s first nuclear weapon occurred at the Trinity Site in New Mexico. The flash from the resulting explosion could be seen 200 miles away; the program was a success. Los Alamos built upon the success of the Trinity testing and later developed the only two nuclear weapons to be used in warfare.

The United States dropped these two bombs, Fat Man and Little Boy, on Imperial Japan who, despite four years of fighting, refused to unconditionally surrender to the Allied Powers. On August 6, 1945, the Enola Gay dropped the first atomic bomb, code named Little Boy, on the Japanese city of Hiroshima. Three days later, Fat Man was dropped on the Japanese city of Nagasaki. After being subjected to two nuclear blasts, the Imperial Japanese military surrendered on August 14, 1945.

The Manhattan Project officially ended in 1946 after absorption into the Atomic Energy Commission.


Independence Hall Association. “The Manhattan Project.” 2016. Accessed September 04, 2016.

Independence Hall Association. “The Decision to Drop the Bomb.” 2016. Accessed September 04, 2016.

Nuclear Age Peace Foundation. “Key Issues: Nuclear Weapons: History: Pre Cold War: Manhattan Project.” Nuclear Files. 2016. Accessed September 04, 2016.

The American Museum of Natural History. “The Manhattan Project.” The American Museum of Natural History. 2016. Accessed September 04, 2016.