This section provides an overview of the history of the Manhattan Project, the key organizations involved, the science behind the bomb, and more.
Manhattan Project Insignia. By Aaron Sauers, Argonne National Laboratory

Atomic Glossary

Some of the terms encountered when perusing the website can be confusing or obscure. This glossary is provided to assist readers and learners of Manhattan Project history.
The Japanese attack on Pearl Harbor

Attack on Pearl Harbor - 1941

The Japanese attack on Pearl Harbor brought the US into World War II.
Photo courtesy of the National Archives

Bataan Death March

On April 9, 1942, the American troops on the Bataan Peninsula of the Philippines surrendered to the Japanese. The captured men were then subjected to the torturous Bataan Death March.
Franklin Roosevelt and Winston Churchill at Casablanca. Photo courtesy of NARA.

Big Science - 1942

President Franklin D. Roosevelt authorized the research, development, and production of an atomic bomb despite great uncertainties.
After the bombing of Hiroshima

Bombings of Hiroshima and Nagasaki - 1945

The first atomic bomb, Little Boy, was dropped on Japan on August 6, 1945.
Schermerhorn Hall at Columbia University. Photo courtesy of Columbia University.

Breakthroughs - 1942

During the first half of 1942, several routes to a bomb were explored.
William Penney, Otto Frisch, Rudolf Peierls, and John Cockroft. Photo courtesy Atomic Heritage Foundation.

Britain's Early Input - 1940-41

The Frisch-Peierls Memorandum was an important assessment confirming the feasibility of an atomic bomb.

British Nuclear Program

The story of U.S.-U.K. nuclear partnership is one of both collaboration and division.
U.S. and Spanish officials with the recovered fourth bomb after the Palomares incident.

Broken Arrow Accidents

The U.S. military uses the term “Broken Arrow” to refer to an accident that involves nuclear weapons or nuclear weapons components.