when did the manhattan project began and end
Timeline of the Manhattan Project The Manhattan Project was a research and development project that produced the first atomic bombs during World War II. It was led by the United States with the support of the United Kingdom and Canada. From 1942 to 1946, the project was under the direction of Major General Leslie Groves of the US Army Corps of Engineers. The Army component of the project was designated the Manhattan District; "Manhattan" gradually became the codename for the entire project. Along the way, the project absorbed its earlier British counterpart, Tube Alloys. The Manhattan Project began modestly in 1939, but grew to employ more than 130,000 people and cost nearly US$2 billion (about $27 billion in 2017[1] dollars). Over 90% of the cost was for building factories and producing the fissionable materials, with less than 10% for development and production of the weapons.[2][3]
Atomic bombings of Hiroshima and Nagasaki The 1943 Quebec Agreement merged the nuclear weapons projects of the United Kingdom and Canada, Tube Alloys and the Montreal Laboratory, with the Manhattan Project,[56][57] under the direction of Major General Leslie R. Groves, Jr., of the U.S. Army Corps of Engineers.[58] Groves appointed J. Robert Oppenheimer to organize and head the project's Los Alamos Laboratory in New Mexico, where bomb design work was carried out.[59] Two types of bombs were eventually developed, both named by Robert Serber. Little Boy was a gun-type fission weapon that used uranium-235, a rare isotope of uranium separated at the Clinton Engineer Works at Oak Ridge, Tennessee.[60] The other, known as a Fat Man device, was a more powerful and efficient, but more complicated, implosion-type nuclear weapon that used plutonium created in nuclear reactors at Hanford, Washington.[61]