This section provides an overview of the history of the Manhattan Project, the key organizations involved, the science behind the bomb, and more.
100 tons of TNT

100-ton TNT Shot

Before the Trinity test, Manhattan Project officials realized that a calibration explosion using ordinary high-explosives would be useful.
The Enola Gay today on display at the National Air and Space Museum Udvar-Hazy Center.

509th Composite Group

The 509th Composite Group was organized as the weapon delivery arm of the Manhattan Project.
African American workers at Oak Ridge during the Manhattan Project

African Americans and the Manhattan Project

African Americans played an important, though often overlooked, role on the Manhattan Project.
German Experimental Pile

Alsos Mission

The Alsos Mission's goal was to learn how close Germany was to developing its own atomic weapon.
A mockup of the accident that killed Louis Slotin.

Atomic Accidents

Although the Manhattan Project was overall a surprisingly safe project, there were a few tragic accidents.
AEC Logo

Atomic Age

The Manhattan Project ushered in the Atomic Age.
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.
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.