After the United States Army Corps of Engineers took over the Manhattan Project in August 1942, the Manhattan District coordinated the work. From 17 February 1943, Compton reported to the director of the Manhattan Project, Brigadier General Leslie R. Groves, Jr., instead of the OSRD S-1 Section. The Manhattan District assumed full responsibility for the Metallurgical Laboratory contract on 1 May 1943. Captain J. F. Grafton was appointed the Chicago Area Engineer in August 1942. He was succeeded by Captain Arthur V. Peterson in December 1942. Peterson remained until October 1944. Captain J. F. McKinley became Chicago Area Engineer on 1 July 1945.