One of the four original numbered air forces, the 4th A.A.F. was activated as the Southwest Air District of the G.H.Q. Air Force on December 18th, 1940, at March Field ( California, United States ). It was redesignated 4th Army Air Force ( 4th A.A.F. ) on March 26th, 1941, with a mission for the defense of the Southwest and Lower Midwest regions of the United States. The 4th A.A.F. was the primary Air Defense Command for the West Coast. The Command also flew antisubmarine patrols along coastal areas of the Gulf of Mexico from after Pearl Harbor ( December 7th, 1941 ) until October 1942.
Beginning in May 1942, the mission of the 4th A.A.F. became operational training of units and crews, and the replacement training of individuals for bombardment, fighter, and reconnaissance operations. The 4th A.A.F. became predominantly a fighter Operational Training Unit ( O.T.U. ) and Replacement Training Unit ( R.T.U. ) organisation. By 1944, most of the Operational Training of groups ended, with the Command concentrating on R.T.U. training of individual replacements using Army Air Force Base Units ( A.A.F.B.U. ) as training organisations at the airfields controlled by the 4th A.A.F. On December 13th, 1944, the 1st, 2nd, 3rd and 4th A.A.F.s were all were placed under the unified command of the Continental Air Forces.
In 1946, it was inactivated, and the 4th A.A.F. was assigned to the post - war Air Defense Command in March, and subsequently to Continental Air Command ( Con.A.C., as the 4th A.F. ) in December 1948 being primarily concerned with air defense. By 1949, with the establishment of the Western Air Defense Force ( W.A.D.F. ), the air defense mission of the Command was transferred to W.A.D.F., leaving the 4th A.F. free to focus on its reserve training tasks, which it did for the next decade.
On September 1st, 1960, Air Defense Command inactivated the 4th A.F., transferring its reserve training mission to the 6th Air Force Reserve Region. The 4th A.F. was re - activated on January 20th, 1966, at Hamilton A.F.B. ( California ), as part of Air Defense Command with the inactivation of its organisation of Air Defense Sectors. The 4th A.F.'s second period of service was short lived, however, and the Command was again inactivated as the result of a major A.D.COM. ( Aerospace Defense Command, former Air Defense Command ) reorganisation on December 31st, 1969 of the 1st, 4th, 10th A.F.s and several Air Divisions. A.D.COM. reassigned the units under the inactivated 4th A.F. were reassigned primarily to the 25th and 26th Air Divisions. The command remained inactive until October 8th, 1976, when it was activated as the 4th A.F. ( Reserve ) at McClellan A.F.B. ( California ), and assigned to the Air Force Reserve.
The 4th A.F. personnel supported operations in Grenada ( " Operation Urgent Fury ", 1983 ) and Panama ( " Operation Just Cause ", 1989 - 1990 ). More than 8,000 Air Force Reservists assigned to the 4th A.F. units served in the United States, Europe, and the Persian Gulf during " Operation Desert Shield " ( 1990 ) and " Desert Storm " ( 1991 ). This included more than 2,878 medical personnel assigned to the 4th A.F. units. The 4th A.F. units routinely support United Nations and Department of State missions.
In 2003, the 4th A.F. became an intermediate echelon responsible primarily for all Air Mobility Command ( A.M.C. ) gained A.F.R.C. air refueling units in the United States and A.M.C. gained A.F.R.C. strategic airlift units in the western United States.
( source : Wikipedia )