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The 4th Air Force was constituted as Southwest Air District on October 19, 1940 and activated on December 18, 1940. It was redesignated 4th AF in early 1941.
The 4th AF provided air defense for the western U.S. until 1943, and training new units.
4th Air Force Patch
Constituted as Southwest Air District on 19 Oct 1 940. Activated on 18 Dec 1940. Redesignated Fourth AF early in 1941. Provided air defense for the western US until 1943, and at the same time trained new organizations. Later, was engaged primarily in training replacements for combat units. Assigned to Air Defense Command in Mar 1946 and to Continental Air Command in Dec 1948, being concerned chiefly with air defense until 1949 and with reserve and national guard activities thereafter.
Commands. IV Bomber: 1941-1944. IV Fighter: 1941-1944. IV Ground Air Support: 1941-1942.
Stations. March Field, Calif, 18 Dec 1940; Riverside, Calif, 16 Jan 1941; Hamilton Field, Calif, 7 Dec 1941; San Francisco, Calif, 5 Jan 1942; Hamilton Field, Calf, 19 Jun 1946-.
Commanders. Maj Gen Jacob E Fickel, 18 Dec 1940; Maj Gen George C Kenney, 2 Apr 1942; Maj Gen Barney McK Giles, 22 Jul 1942; Maj Gen William E Kepner, 18 Mar 1943; Maj Gen William E Lynd, 8 Jul 1943; Maj Gen James E Parker, 14 Jul 1944; Brig Gen Edward M Morris, 19 May 1945; Maj Gen Willis H Hale, 6 Jul 1945; Brig Gen Ned Schramm, 1 Nov 1947; Maj Gen John E Upston, 20 Jan 1948; Maj Gen Alvan C Kincaid, c. Sep 1950; Maj Gen William E Hall, 29 Jan 1951; Maj Gen Alfred A Kessler Jr, 8 Sep 1952; Maj Gen Robert B Landry, 4 Feb 1955-.
Campaigns. American Theater.
Decorations. None.
Insigne. Shield: Azure, a white star, charged with a red disc, all within a white winged annulet upheld by four golden yellow rays, radiating from base point, all within a border of the last. (Approved 1 Sep 1943. This insigne was superseded by another on 21 Mar 1957.)
Data from Air Force Combat Units of World War II By Maurer, Maurer, Published 1986
Fourth Air Force traces its origins to October 19, 1940, when it was constituted as the Southwest Air District, one of four continental regional commands the Army Air Corps organized as prewar mobilization gathered pace. Activated on December 18, 1940, at March Field, California, and redesignated Fourth Air Force in early 1941, the organization carried primary responsibility for defending the western United States, a mission that took on genuine urgency after Pearl Harbor, when fears of a Japanese attack on the West Coast, however overstated in hindsight, drove real investment in coastal air defense infrastructure and readiness.
Fourth Air Force's headquarters moved twice in its early wartime years, from Riverside, California, in January 1941, to Hamilton Field just days after Pearl Harbor, and then to San Francisco in January 1942, moves that reflect both the command's expanding scope and the heightened operational tempo of the war's first anxious months on the West Coast. Regional fighter wings covering Los Angeles, San Diego, San Francisco, and Seattle gave the command a genuinely comprehensive defensive network spanning the entire Pacific coastline, coordinating interceptor response and coastal warning systems across a vast and strategically exposed stretch of American territory.
As the direct invasion threat to the West Coast diminished through 1942 and 1943, Fourth Air Force's mission increasingly shifted toward training, joining its sister continental air forces in the essential work of preparing replacement aircrew and combat units for deployment to the Pacific and other overseas theaters, work that continued for the remainder of the war even as the command's air defense responsibilities gradually wound down.
Fourth Air Force's command history includes one especially notable figure: Major General George C. Kenney, who took command in April 1942 before moving on to lead Fifth Air Force and ultimately the reconstituted Far East Air Forces, where he became one of the Pacific War's most celebrated and innovative air commanders, developing the low-level skip-bombing and parafrag tactics that devastated Japanese shipping and airfields throughout the Southwest Pacific campaign. Kenney's brief but consequential Fourth Air Force tenure represents an important early chapter in a career that would go on to fundamentally shape American tactical airpower doctrine in the Pacific theater. Other Fourth Air Force commanders, including Major General Barney McK. Giles, Major General William E. Kepner, and Major General James E. Parker, guided the command through its evolving air defense and training missions across the remainder of the war.
a. Status, readiness, and supply of US armed forces
Fourth Air Force's rapid headquarters relocations in the immediate aftermath of Pearl Harbor reflect genuine, if ultimately unrealized, readiness anxiety about a possible Japanese attack on the American mainland's West Coast, anxiety that drove real investment in coastal radar, interceptor basing, and civilian air raid warning coordination during the war's early months. As that threat receded through 1942, the command's resources and infrastructure were increasingly reallocated toward training capacity, a readiness pivot mirroring the broader pattern seen across all four continental numbered air forces as the true nature and geography of the war became clearer to American planners.
b. Development of fighting men and command structures
Fourth Air Force's network of regional fighter wings, each covering a major West Coast metropolitan area, gave the command a genuinely decentralized but coordinated air defense structure well-suited to covering an enormous coastline with limited resources, a command architecture that balanced local responsiveness with centralized strategic direction. As the command's mission shifted toward training, this same distributed infrastructure proved readily adaptable to hosting the flight schools, replacement training units, and combat crew preparation programs the western training mission required for the remainder of the war.
c. Prominent personnel and their role with the organization
Major General George C. Kenney's April 1942 to July 1942 tenure commanding Fourth Air Force, though brief, represents a significant early milestone in the career of one of the Pacific War's most influential air commanders; Kenney's subsequent command of Fifth Air Force and the Far East Air Forces, where he pioneered tactics that dramatically increased Allied airpower's effectiveness against Japanese shipping and airfields, gives his stateside Fourth Air Force command added historical significance as an important, if often overlooked, stop on the path to his Pacific theater achievements. Kenney's successors, including Major General Barney McK. Giles (who went on to serve as Deputy Commanding General of the Army Air Forces) and Major General William E. Kepner (who had commanded VIII Fighter Command in England), reflect a broader pattern of experienced, combat-tested officers rotating through Fourth Air Force leadership, bringing hard-won operational insight into its continuing readiness and training missions.
Q1: When was the Fourth Air Force established?
A1: The Fourth Air Force was constituted as the Southwest Air District on October 19, 1940, activated December 18, 1940, and redesignated Fourth Air Force in early 1941.
Q2: What was Fourth Air Force's WWII mission?
A2: Fourth Air Force provided air defense for the western United States until 1943 while simultaneously training new units, later shifting primarily to training replacements for combat units overseas.
Q3: Who commanded Fourth Air Force before leading Pacific air operations?
A3: General George C. Kenney commanded Fourth Air Force from April 1942 before moving on to command Fifth Air Force and later the Far East Air Forces in the Southwest Pacific.
Q4: Where was Fourth Air Force headquartered?
A4: Fourth Air Force was based at March Field, California, moving its headquarters to Riverside in January 1941 and later to Hamilton Field and San Francisco.
Q5: What subordinate commands did Fourth Air Force oversee?
A5: Fourth Air Force controlled IV Bomber Command, IV Fighter Command, and IV Ground Air Support Command, along with regional fighter wings covering Los Angeles, San Diego, San Francisco, and Seattle.
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