The Manhattan project was led by the United States and the United Kingdom. It produced one of the first nuclear weapons during world war two. Most of the scientist that came to organize this project for military purposes came usually from Europe. On December 6, 1941 the project was put under the direction of the office of scientific research and development, headed by Vannevar Bush. After the United States entry into world war two, the war department was given responsibility for the project, because by mid-1942 it was obvious that pilot plants, laboratories, and manufacturing facilities would have to be constructed by the U.S. Army Corps of Engineers so that the assembled scientists could carry out their mission. During 1940 German scientists
