Lieutenant General Leslie Groves (1896-1970) was a United States Army Corps of Engineers officer and director of the Manhattan Project. In September 1942, Groves was appointed to head the Manhattan Project with the rank of Temporary Brigadier General. As project leader, he was in charge of all of the project's phases, including scientific, technical and process development; construction; production; security and military intelligence of enemy activities; and planning for use of the bomb. Under General Groves' direction, atomic research was conducted at Columbia University and the University of Chicago. The main project sites were built at Los Alamos, Oak Ridge, and Hanford. He personally selected J. Robert Oppenheimer as leader of the Los Alamos laboratory, disregarding the latter man's Communist associations and waiving his security clearance process. Groves was known for his critical and stubborn attitude, egotism, intelligence, and drive to achieve his goals at all costs. He continued to lead the project until 1947, when atomic energy affairs were turned over to the newly created civilian Atomic Energy Commission.