The United States Atomic Energy Commission (AEC) was an agency of the United States government established after World War II by Congress to foster and control the peacetime development of atomic science and technology. President Harry S. Truman signed the McMahon/Atomic Energy Act on August 1, 1946, transferring the control of atomic energy from military to civilian hands, effective from January 1, 1947. Public Law 585, 79th Congress. This shift gave the first members of the AEC complete control of the plants, laboratories, equipment, and personnel assembled during the war to produce the atomic bomb.