Formed as a B-18 Bolo bombardment squadron under Third Air Force in Louisiana during 1940. Re-equipped with A-24 Dauntless Dive Bombers, then in late 1941, ordered to Seventh Air Force in the Philippines in response to the growing crisis in the Pacific. Ground echelon arrived in Philippines in late November 1941, however outbreak of World War II in the Pacific caused A-24 aircraft to be diverted to Australia. Portions of air echelon flew to Australia to pick up aircraft, however Japanese advance in the Philippines prevented their return. Personnel in the Philippines reassigned as ground infantry unit and engaged the enemy on Luzon during the ground Battle of Bataan. Some personnel were evacuated to Australia by submarine. After collapse of organized United States resistance in May 1942, survivors endured Bataan Death March or continued as unorganized resistance forces in the Occupied Philippines.



Air Echelon reorganized in Australian Northern Territory and fought in Dutch East Indies and New Guinea Campaigns until equipment depleted. Was inactivated in place and squadron administratively activated at Hunter Field, Georgia. Re-equipped first with A-20 Havocs then A-36 Apache fighter-bombers in the United States, then deployed to North Africa, assigned to Twelfth Air Force. Re-designated as 523d Fighter-Bomber Squadron in August 1943 after Sicilian Campaign. Re-equipped with P-40 Warhawks, then P-47 Thunderbolts and engaged enemy forces as a tactical fighter squadron during the Italian Campaign. Supported ground forces in the Invasion of Southern France and drive northwards though Lyon until linking with Allied ground forces in eastern France. Returned to Italy and engaged enemy forces in the Po Valley, then returning to France in the spring of 1945 and supporting ground forces during the Western Allied invasion of Germany in March/April 1945. Squadron demobilized in Germany summer 1945, being inactivated as a paper unit in November 1945.