This section provides an overview of the history of the Manhattan Project, the key organizations involved, the science behind the bomb, and more.
Former HUAC Chairman J. Parnell Thomas

HUAC and the Manhattan Project

A number of scientists associated with the Manhattan Project were eventually investigated by the House Un-American Activities Committee.
Operation at Oak Ridge Hospital, 1944

Human Radiation Experiments

Between April 1945 and July 1947, eighteen subjects were injected with plutonium, six with uranium, five with polonium, and at least one with americium in order to better understand the effects of radioactive materials on the human body.
Bravo thermonuclear test

Hydrogen Bomb - 1950

In January 1950, President Truman made the controversial decision to continue and intensify research and production of thermonuclear weapons.
The logo of the Bhabha Atomic Energy Commission

Indian Nuclear Program

India tested its first atomic bomb in 1974 but did not develop a significant nuclear arsenal until more than two decades later.

Isotope Separation Methods

How to separate the much more potent U-235 from its abundant relative, U-238 consumed thousands of hours and millions of dollars.
An American satellite image of the Dimona nuclear complex, 1968

Israeli Nuclear Program

Israel is widely believed to possess nuclear weapons, but has never confirmed the existence of its nuclear program.
A Japanese cyclotron constructed after the war

Japanese Atomic Bomb Project

Japan initiated multiple small efforts to pursue an atomic bomb, but all were unsuccessful.
Photo courtesy of the National Archives and Records Administration

Japanese Balloon Bombs "Fu-Go"

On November 3, 1944, Japan released fusen bakudan, or balloon bombs, into the Pacific jet stream. Japan’s latest weapon, the balloon bombs were intended to cause damage and spread panic in the continental United States.
Japanese resistance fighters captured

Japanese Mass Suicides

The War of the Pacific against Imperial Japan was marked by episodes of mass suicides by Japanese soldiers and civilians, notably in Saipan and Okinawa.