Organized in 1921 as the 28th Squadron (Bombardment) in the permanent United States Army Air Service, the squadron served in the Philippines during the Inter-War period, engaging in combat during the 1941–42 Battle of the Philippines at the beginning of World War II. Withdrawn to Australia, it fought in the Dutch East Indies campaign before returning to the United States and being re-equipped with Boeing B-29 Superfortress bombers. It returned to the Pacific Theater of Operations in early 1945 to carry out strategic bombing missions over the Japanese Home Islands.