20th Air Base Group

The first predecessor of the group was the 66th Aero Squadron,[note 1] which was organized in April 1918 at Kelly Field, Texas. As soon as the squadron was organized it moved to Eberts Field, Arkansas to join the flying school there. In the summer of 1918, the Air Service reorganized its units at its flying schools as lettered squadrons and the squadron became Squadron A, Eberts Field.[2] Shortly after the end of the World War I, the squadron was demobilized and its personnel were absorbed by the Flying School Detachment at Eberts Field.

In June 1921, Air Park No. 11 was organized at Clark Field, Philippines, moving to what became Nichols Field before the end of the year. In 1923, the Air Service renamed its air parks as service squadrons and the unit became the 66th Service Squadron,[2] with the mission of providing second level maintenance for the aircraft of the 4th Composite Group at Nichols. Due to post-war shortages in officers, garrison units in the Philippines were manned assigned only 50% of their authorized officer personnel through the first half of the 1920s.[3]

In 1936 the Air Corps consolidated many of its World War I Aero Squadrons with units formed after the war but bearing the same number, and the old 66th Aero Squadron was consolidated with the post-war 66th Squadron.[2]

In 1938, the Air Corps reorganized its support units and the 66th was consolidated with the Station Complement, Nichols Field as the Base Headquarters and 20th Air Base Squadron. In the fall of 1940, air base squadrons expanded into groups and were assigned materiel squadrons for maintaining aircraft and air base squadrons to provide administrative support, and the unit became the 20th Air Base Group.[1]

The 20th Group's station at Nichols Field came under Japanese air attack as World War II began in the Pacific. Although Far East Air Force had built up to the largest American overseas force in terms of personnel, much of its equipment was en route when the Japanese attacked.[4] As the war began, the group supported the 2d Observation Squadron, 17th Pursuit Squadron and 34th Pursuit Squadron at Nichols.[5] Three days after the start of the war, 10 December 1941, saw the first concentrated Japanese attacks on Nichols. By the end of the attack all observation airplanes at Nichols had been destroyed or rendered unserviceable.[6] By 24 December, all bombers had been flown to Australia and air force headquarters and all combat units except for a few fighters soon followed.[7][8]

By the end of December, all American forces were being withdrawn to Bataan. Colonel Harold H. George, of 5th Interceptor Command assumed control of all Air Corps units remaining in the Philippines. With the flying mission being performed by a handful of fighter pilots, the bulk of the group's personnel were employed as infantry.[9] By May 1942, resistance in the Philippines had ended and the group ceased to exist as an organized military formation.

• Primary Flying School, Eberts Field, 26 April 1918 – 15 November 1918
• 1st Group (Composite) (later 4th Composite Group), 2 June 1921[2]
• Philippine Department, 1 September 1936
• Philippine Department Air Force (later Far East Air Force), 20 September 1941
• Far East Air Service Command (later 5th Air Force Base Command, 5th Air Force Service Command, V Air Force Service Command), 16 November 1942 – 2 April 1946[11]

• Kelly Field, Texas, 26 April 1918
• Eberts Field, Arkansas, ca. 1 May 1918 – 15 November 1918
• Clark Field, Philippines, 2 June 1921[2]
• Camp Nichols (later Nichols Field), Philippines, 21 December 1921[2] – 1942

• Air Base Squadron, 20th Air Base Group (later 19th Air Base Squadron), 1 September 1940 – 2 April 1946
• 1st Materiel Squadron, 20th Air Base Group (later 27th Material Squadron), 1 September 1940 – 2 April 1946
• 2d Materiel Squadron, 20th Air Base Group (later 28th Material Squadron), 1 September 1940 – 2 April 1946
• 745th Ordnance Company, Aviation (Air Base), attached, c. May 1941 – 2 April 1946
• Air Corps Detachment, Weather, Philippines, 2 January–20 September 1941[12]

• Clay, Steven E. (2011). US Army Order of Battle 1919-1941 (PDF). Vol. 3 The Services: Air Service, Engineers, and Special Troops 1919-1941. Fort Leavenworth, KS: Combat Studies Institute Press. ISBN 978-0-98419-014-0. LCCN 2010022326. OCLC 637712205. Archived from the original (PDF) on 27 September 2013. Retrieved 16 October 2012.
• Markus, Rita M.; Halbeisen, MSG Nicholas F.; Fuller, John F. (1987). Matthews, James K.; Gustin, Joylyn I. (eds.). Air Weather Service: Our Heritage 1937-1987 (PDF). Scott AFB, IL: Air Weather Service. OCLC 18406969. Retrieved 10 June 2017.
• Maurer, Maurer (1987). Aviation in the U.S. Army, 1919-1939 (PDF). Washington, DC: Office of Air Force History, United States Air Force. ISBN 0-912799-38-2. LCCN 87012257. OCLC 15661556. Retrieved 17 December 2016.
• Maurer, Maurer, ed. (1983) [1961]. Air Force Combat Units of World War II (PDF) (reprint ed.). Washington, DC: Office of Air Force History. ISBN 0-912799-02-1. LCCN 61060979. Retrieved 17 December 2016.
• Williams, E. Kathleen (June 1945). "Army Air Forces in the War Against Japan, 1941-1942, USAF Historical Study No. 34" (PDF). Assistant Chief of Staff Intelligence, Historical Division. Retrieved 16 May 2017.
• "AF Pamphlet 900-2, Unit Decorations, Awards and Campaign Participation Credits" (PDF). Washington, DC: Department of the Air Force Index. 15 June 1971. Archived from the original (PDF) on 4 August 2015. Retrieved 11 August 2016.