During World War II, its predecessor unit, the 17th Bombardment Squadron (Light) fought in the Philippines Campaign (1941–1942). Its ground personnel fought as infantry in the 1941-1942 Battle of Bataan with the survivors being forced to march as prisoners in the Bataan Death March. The squadron reformed with its present numerical designation, and by the end of World War II, the Airmen of the 523d were among the most decorated USAAF units of the war, having fought in the North African, Sicilian, Italian and Southern France campaigns in the European Theater.