The 363rd Air Expeditionary Operations Group has its origins to World War II 363d Fighter Group, being activated on 1 August 1943 at Hamilton Field, California. Initially a IX Fighter Command tactical fighter group, the unit was credited with 41 victories but lost 43 of its own aircraft in the process.

Being activated on 1 August 1943 at Hamilton AAFld, California. The original fighter squadrons (380th, 381st, 382d) trained with Bell P-39 Airacobras at Hamilton and other airfields in California and served as part of the air defense force.

The group moved to England in December 1943 for duty with the Ninth Air Force. At RAF Keevil, the group was re-equipped with North American P-51 Mustang in January 1944 and entered combat in February. Squadron designations were changed to 160th (A9), 161st (B3) and 162d (C3) Fighter Squadrons and assigned Fuselage Codes. The group escorted bombers and fighter-bombers to targets in France, Germany, and the Low Countries; strafed and dive-bombed trains, marshalling yards, bridges, vehicles, airfields, troops, gun positions, and other targets on the Continent.

The 363d supported the D-Day invasion of Normandy in June 1944 by escorting troop carriers and gliders and by attacking enemy positions near the front lines, and moved to the Continent at the end of June to take part in the Allied drive to the German border.

In the two weeks following D-Day, the 363d experienced the most fruitful period of its service in the European Theater of Operations when patrols over France brought it actions with a total of 19 confirmed victories. However, a similar number of Mustangs were lost, albeit mostly to ground fire.

The pressing need for tactical aerial reconnaissance during the Normandy Campaign led the group to be converted to a photo-reconnaissance Group with the 363d Tactical Reconnaissance Group being formed at Le Mans, France in late 1944. The 363d TRG was the 'eyes' of General George S. Patton's Third Army during its advance through France, and later during the Allied invasion of Germany in 1945.