<P> Working in collaboration with the United Kingdom and Canada , with their respective projects Tube Alloys and Chalk River Laboratories , the Manhattan Project , under the direction of Major General Leslie R. Groves , Jr. , of the U.S. Army Corps of Engineers , designed and built the first atomic bombs . 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 . Two types of bombs were eventually developed . 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 . The other , known as a Fat Man device ( both types named by Robert Serber ) , was a more powerful and efficient , but more complicated , implosion - type nuclear weapon that used plutonium created in nuclear reactors at Hanford , Washington . A test implosion weapon , the gadget , was detonated at Trinity Site , on July 16 , 1945 , near Alamogordo , New Mexico . </P>
<P> Working in collaboration with the United Kingdom and Canada , with their respective projects Tube Alloys and Chalk River Laboratories , the Manhattan Project , under the direction of Major General Leslie R. Groves , Jr. , of the U.S. Army Corps of Engineers , designed and built the first atomic bombs . 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 . Two types of bombs were eventually developed . 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 . The other , known as a Fat Man device ( both types named by Robert Serber ) , was a more powerful and efficient , but more complicated , implosion - type nuclear weapon that used plutonium created in nuclear reactors at Hanford , Washington . A test implosion weapon , the gadget , was detonated at Trinity Site , on July 16 , 1945 , near Alamogordo , New Mexico . </P>
where were the hiroshima and nagasaki bombs made
where were the hiroshima and nagasaki bombs made
Los Alamos Laboratory in New Mexico
Los Alamos Laboratory in New Mexico