Manhattan Project

'Calutron Girls' monitoring a mass spectrometer during the Manhattan Project. Gladys Owens, in the foreground, did not know what she was involved with until seeing this picture on a tour fifty years later.
'Calutron Girls' monitoring a mass spectrometer during the Manhattan Project. Gladys Owens, in the foreground, did not know what she was involved with until seeing this picture on a tour fifty years later.

Historical Context

The Manhattan Project was the codename for the American effort to develop and test nuclear weapons during World War II. Run by General Leslie Groves, the construction of the actual bomb was overseen by Robert Oppenheimer, who was head of the Los Alamos Laboratory where it was developed.

In 1939 a letter written by Leo Szilard and signed by Albert Einstein was delivered to US President Franklin D. Roosevelt. The letter urged the United States to develop uranium stockpiles and commence research efforts, especially as Nazi Germany might do the same.

Two bomb types were developed: Little Boy, a uranium bomb, and Fat Man, a plutonium bomb. The work was carried out with extreme secrecy; many of those working on the project had no idea what they were working towards. Despite the security, Soviet spies managed to penetrate the project, and were aware that the US had developed the bomb.

On July 16, 1945, the Trinity test became the first detonation of a nuclear weapon. Less than a month later, President Harry Truman authorized the use of nuclear weapons on Hiroshima and Nagasaki, to date the only use of nuclear weapons in history. The bombs brought about the quick end of World War II without the need for a catastrophic invasion of Japan, but with an exceptionally high loss of civilian life in the two destroyed cities.

Photo Info


Photographer: Ed Westcott
Location taken: Oak Ridge, Tennessee, USA

Source: Wikimedia Commons

Related Events

  • 1941-10-09 US President Franklin D. Roosevelt approves an atomic program that would become the Manhattan Project
  • 1942-08-13 The 'Manhattan Project' commences, under the direction of US General Leslie Groves: its aim - to deliver an atomic bomb
  • 1945-01-15 The Manhattan Project's G-5 Group, headed by Physicist's Donald Kerst and Seth Neddermeyer, take their first betatron pictures of a nuclear implosion at the Los Alamos Laboratory
  • 1945-07-16 1st test detonation of an atomic bomb, Trinity Site, Alamogordo, New Mexico as part of the US Manhattan Project

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