Field, the 3rd was most likely an observer training unit in support of the United States Army Field Artillery School. In September 1917, the 4th Aero Squadron was transferred to Post Field from Fort Sam Houston, as a second training squadron. The 3rd was ordered to transfer 135 men to the 4th to bring the squadron up to its authorized strength. The 3rd was redesignated as "Squadron A", with the 4th being redesignated as "Squadron B" in July 1918. Both squadrons were demobilized at the end of World War I on 2 January 1919. Philippines Duty The unit was re-formed as a new unit, designated as the 3rd Aero Squadron, on 13 May 1919 at Mitchel Field, New York. Many of the men were experienced mechanics and officers who had served either in France or at training units in the United States during World War I. After being organized, the squadron was transferred by train to San Francisco, California, where it boarded a ship bound for Manila, in the Philippine Islands, arriving on 18 August. The squadron was assigned to the Philippine Department, and was stationed initially at Camp Stotsenburg on Luzon. Some Dayton-Wright DH-4s, which were used as trainers during the war in the United States, arrived later in 1919 and were assigned to the squadron. On 10 March 1920, along with the 2d Aero Squadron, which had arrived in December 1919, the squadrons were organized into the 1st Group (Observation). On 14 March 1921, the squadron was re-designated as the 3rd Squadron (Pursuit), its mission was to provide coastal aerial defense as part of the 4th Composite Group, a re-designation of the 1st Group. In 1924, the squadron was formally consolidated with its World War I predecessor organization, giving it a history dating to 1 November 1916. Exercises and maneuvers with Army ground forces and Naval forces were a regular and important part of its mission. In the Philippines, the squadron received a wide variety of second-line hand-me-down aircraft transferred from units in the United States during the austere years of Air Corps procurement during the 1920s and 1930s As a result of the rising tensions with the Japanese Empire in 1940, the defenses of the Philippines were judged to be abysmal, and a reinforcement effort was made to defend the islands against any Japanese aggression. The 3rd had received P-26 Peashooters in 1937, the latest in the