Editing 20th Air Base Group (section)

==History==
===World War I===
The first predecessor of the [[group (military aviation unit)|group]] was the '''66th Aero Squadron''',<ref group=note>The unit is not related to an earlier 66th Aero Squadron, organized in August 1917, which had been renumbered as the 478th Aero Squadron (Construction).</ref> which was organized in April 1918 at [[Kelly Field]], Texas.  As soon as the squadron was organized it moved to [[Eberts Field (Airport)|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'''.<ref name=Clay1421>Clay, p. 1421</ref> 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.

===Interwar years in the Philippines===
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''',<ref name=Clay1421/> 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.<ref>Maurer, ''Aviation in the U.S. Army'', p. 50</ref>

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.<ref name=Clay1421/>

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'''.<ref name=Clay1639/>

===Defense of the Philippines===
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.<ref>Williams, p. 20</ref> As the war began, the group supported the [[2d Observation Squadron]], [[17th Pursuit Squadron]] and [[34th Pursuit Squadron]] at Nichols.<ref>Williams, p. 26</ref> 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.<ref>Williams, p. 35</ref> By 24 December, all [[bomber]]s had been flown to Australia and air force headquarters and all combat units except for a few [[fighter aircraft|fighters]] soon followed.<ref>Williams, p. 32</ref><ref>Maurer, ''Combat Units'', p. 461</ref>

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.<ref>Williams, pp. 36-37</ref> By May 1942, resistance in the Philippines had ended and the group ceased to exist as an organized military formation.