Flying the Republic P-47 Thunderbolt, the 56th Fighter Group was the most successful of the Eighth Air Force groups in air-to-air combat, and the second most successful in the USAAF with 665.5 (the 354th FG had 701 while the Pacific-based 49th FG had 664). It engaged in counter-air and interdictory missions during the invasion of Normandy in June 1944. Supported Allied forces for the breakthrough at Saint-Lô in July and participated in the Battle of the Bulge, December 1944-January 1945. Helped to defend the Remagen bridgehead against air attacks in March 1945.