Events

The events of the Manhattan Project have been grouped under the time periods listed to the left. A quick overview of the Manhattan Project can be obtained by reading the summaries on each of the eight "Time Periods" pages, located in the left navigation bar. Each summary page also has a listing of the events pages for that particular time period.

1890s-1939: Atomic Discoveries

A Miniature Solar System, 1890s-1919
Exploring the Atom, 1919-1932
Atomic Bombardment, 1932-1938
The Discovery of Fission, 1938-1939
Fission Comes to America, 1939

1939-1942: Early Government Support

Einstein's Letter, 1939
Early Uranium Research, 1939-1941
Piles and Plutonium, 1939-1941
Reorganization and Acceleration, 1940-1941
The MAUD Report, 1941
A Tentative Decision to Build the Bomb, 1941-1942

1942: Difficult Choices

More Uranium Research, 1942
More Piles and Plutonium, 1942
Enter the Army, 1942
Groves and the MED, 1942
Picking Horses, November 1942
Final Approval to Build the Bomb, December 1942

1942-1944: The Uranium Path to the Bomb

Y-12: Design, 1942-1943
Y-12: Construction, 1943
Y-12: Operation, 1943-1944
Working K-25 into the Mix, 1943-1944
The Navy and Thermal Diffusion, 1944

1942-1944: The Plutonium Path to the Bomb

Production Reactor (Pile) Design, 1942
DuPont and Hanford, 1942
CP-1 Goes Critical, December 2, 1942
Seaborg and Plutonium Chemistry, 1942-1944
Final Reactor Design and X-10, 1942-1943
Hanford Becomes Operational, 1943-1944

1942-1945: Bringing It All Together

Establishing Los Alamos, 1942-1943
Early Bomb Design, 1943-1944
Basic Research at Los Alamos, 1943-1944
Implosion Becomes a Necessity, 1944
Oak Ridge and Hanford Come Through, 1944-1945
Final Bomb Design, 1944-1945
Atomic Rivals and the ALSOS Mission, 1938-1945
Espionage and the Manhattan Project, 1940-1945

1945: Dawn of the Atomic Era

The War Enters Its Final Phase, 1945
Debate Over How to Use the Bomb, Late Spring 1945
The Trinity Test, July 16, 1945
Safety and the Trinity Test, July 1945
Evaluations of Trinity, July 1945
Potsdam and the Final Decision to Use the Bomb, July 1945
The Atomic Bombing of Hiroshima, August 6, 1945
The Atomic Bombing of Nagasaki, August 9, 1945
Japan Surrenders, August 10-15, 1945
The Manhattan Project and the Second World War, 1939-1945

1945-present: Postscript -- The Nuclear Age

Informing the Public, August 1945
The Manhattan Engineer District, 1945-1946
First Steps toward International Control, 1941-1945
Search for a Policy on International Control, 1945
Negotiating International Control, 1945-1946
Civilian Control of Atomic Energy, 1945-1946
Operation Crossroads, July 1946
The VENONA Intercepts, 1946-1980
The Cold War, 1945-1990
Nuclear Proliferation, 1949-present

Sources and notes for this page.

The text for this page is original to the Department of Energy's Office of History and Heritage Resources. The photograph of Albert Einstein with Leo Szilard is courtesy the Federation of American Scientists.