Manhattan Project

World War 2

What was the Manhattan Project?

The Manhattan Project was a secret military project created in 1942 to produce the first US nuclear weapon. Fears that Nazi Germany would build and use a nuclear weapon during World War II triggered the start of the Manhattan Project, which was originally based in Manhattan, New York.

Who and Where?

The main assembly plant was built at LOS ALAMOS, NEW MEXICO. ROBERT OPPENHEIMER was put in charge of putting the pieces together at Los Alamos. After the final bill was tallied, nearly $2 billion had been spent on research and development of the atomic bomb. The Manhattan Project employed over 120,000 Americans.
Robert Oppenheimer was an American theoretical physicist and professor of physics at the University of California, Berkeley. He was the main scientist for the Manhattan Project.


Secrecy was very important. Neither the Germans nor the Japanese could learn of the project. Roosevelt and Churchill also agreed that the Stalin would be kept in the dark. Consequently, there was no public awareness or debate. Keeping 120,000 people quiet would be impossible; therefore only a small privileged cadre of inner scientists and officials knew about the atomic bomb's development. In fact, Vice-President Truman had never heard of the Manhattan Project until he became President Truman.

The First Test Run

By the summer of 1945, Oppenheimer was ready to test the first bomb. On July 16, 1945, at TRINITY SITE near ALAMOGORDO, NEW MEXICO, scientists of the Manhattan Project readied themselves to watch the detonation of the world's first atomic bomb. The device was affixed to a 100-foot tower and discharged just before dawn. No one was properly prepared for the result. A blinding flash visible for 200 miles lit up the morning sky. A mushroom cloud reached 40,000 feet, blowing out windows of civilian homes up to 100 miles away. When the cloud returned to earth it created a half-mile wide crater metamorphosing sand into glass. A bogus cover-up story was quickly released, explaining that a huge ammunition dump had just exploded in the desert.

Though it eventually included over 30 different research and production sites, the Manhattan Project was chiefly carried out in three secret scientific cities: Hanford, Washington, Oak Ridge, Tennessee, and Los Alamos, New Mexico.