The 48th constructed and maintained airfields and related facilities in France between 1917 and 1919. It trained aviation personnel from 1927 to 1931 and from 1933 to 1936. The squadron was equipped with P-38 Lightnings in 1941 and assigned to Hamilton Field, California. From 5 February to 3 June 1942 it flew air defense patrols along the California coast. It was deployed to the European Theater of Operations (ETO) in August 1942 to fly escort missions of B-17 and B-24 heavy bombers as part of VIII Fighter Command.