March 9, 1942, the Air Service Command now became one of the major AAF commands, with relatively clear lines of responsibility and authority. Four air service area commands (San Antonio, Fairfield, Middletown, and Sacramento?), successors to the maintenance wings (and field service sections, originally activated in 1940?), had been activated in December 1941 to supervise the depots in given geographical areas. The depots, of which there were eleven by April 1942, became the centers of depot control areas, which directed the activities of subdepots within defined geographical limits. Unfortunately, the boundaries of some of the depot control areas overlapped those of air service areas, and since the depots were the real focal points of supply and maintenance activities, the air service areas never attained the status of fully functioning ASC subcommands. The air service areas were disbanded on February 1, 1943, to be succeeded by air depot control area commands, which were simply the eleven former depot control areas under a new name. The elimination of the four air service areas was apparently justified by subsequent operations; according to Maj. Gen. Walter H. Frank, commander of the ASC, the step proved "most beneficial." In May 1943 the air depot control area commands were redesignated air service commands with appropriate geographical designations, and from then to the end of the war the ASC conducted its operations in the continental United States through its eleven air service commands, each serving a separate geographical area. These air service commands included the Middletown Air Service Command (Olmsted Field, Middletown, Pennsylvania), Mobile ASC, Ogden Air Service Command, Oklahoma City Air Service Command, Rome Air Service Command, Sacramento Air Service Command, the San Antonio Air Service Command, the San Bernardino Air Service Command, Warner Robins Air Service Command, Warner Robins, as well as five-six others. In 1944 the air service commands were redesignated air technical service commands. The Materiel Division was assumed responsibility for R&D and procurement, and was redesignated Air Corps Materiel Command on April 1, 1942. This became Air Force Materiel Command in April 1942; Materiel Command in April 1943, and AAF Materiel Command on January 15, 1944. On July 17, 1944, Air Service Command and AAF Materiel Command were placed under a new organization, AAF Materiel and Services. On August 31, 1944, AAF Materiel and Services was redesignated Army Air Forces Technical Service Command. The 4000th Army Air Forces Base Unit (Command) was