In 1939, German physicists had learned how to split a uranium atom. Two renowned scientists—Albert Einstein and Enrico Fermi—had fled fascist Germany and Italy and found refuge in the United States. These two urged President Roosevelt to establish an atomic research program. Roosevelt agreed, but wanted to proceed slowly. In 1941, the Manhattan Project was established to design and build an atomic bomb.

By December 1942 Fermi led a group of physicists to produce the first controlled nuclear chain reaction. This accomplishment led to more funding, and the project advanced rapidly. Nuclear facilities were built at Oak Ridge, Tennessee and Hanford, Washington. The main assembly plant was built at Los Alamos, New Mexico. Nearly $2 billion was spent on research and development of the atomic bomb. The Manhattan Project employed over 120,000 Americans.

Secrecy was critical so that neither the Germans nor the Japanese would learn of the project. As a result, the American public was also unaware of the Manhattan Project. Only a small privileged group of scientists and officials knew about the atomic bomb's development. Most of the people working on it did not know where their work was headed. Despite the attempt at secrecy, a Soviet spy did penetrate the group and learn about the development of the bomb.

On July 16, 1945, scientists of the Manhattan Project gathered in New Mexico 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.

A blinding flash lit up the morning sky. A mushroom cloud reached 40,000 feet. Windows blew out in civilian homes up to 100 miles away. The explosion created a half-mile wide crater and turned the sand into glass. The government released a cover-up story claiming that a huge ammunition dump had exploded in the desert.

Source: The Manhattan Project
Copyright ©2008-2022 ushistory.org, owned by the Independence Hall Association in Philadelphia, founded 1942.