The 4th Fighter Group was an American element of the United States Army Air Forces (USAAF) Eighth Air Force during World War II. The group was known as the Debden Eagles because it was created from the three Eagle Squadrons of the Royal Air Force: No. 71, No. 121 Squadron RAF, and No. 133 Squadron RAF. These squadrons became the 334th, 335th, and 336th Fighter Squadrons of the 4th Fighter Group based at RAF Debden. The group was the first fighter group to fly combat missions over German airspace, the first to escort bombers over Berlin, and the first selected to escort bombers on shuttle bombing runs landing in Russia. The group was credited with shooting down 1,016 German planes. Eagle Squadrons The Eagle Squadrons were formed in 1940 with volunteer pilots from the United States prior to its entry into World War II in December 1941. The three Eagle Squadrons formed between September 1940 and July 1941 were turned over to the Eighth Air Force. They existed until 29 September 1942 and became the 4th Fighter Group of the United States Army Air Forces Eighth Air Force. The 71, 121, and 133 squadrons became the 334th, 335th and 336th Fighter Squadron and transferred as complete units. European theatre The group was briefly at RAF Bushey Hall before moving to Debden in late September, 1942. They served in combat over Europe from October 1942 to April 1945 and was the longest serving USAAF fighter group in the European theatre of World War II. It was assigned to VIII Fighter Command, September 12, 1942 and the 4th Air Defense (later, 65th Fighter) Wing, July 1943 – November 1945. The group operated until April 1, 1943 using Spitfires aircraft. Aircraft were changed to P-47 Thunderbolts on April 1, 1943 and then to P-51 Mustangs on February 25, 1944. The 4th was the first group to escort U.S. bombers over Berlin on March 4, 1944. The group earned Distinguished Unit Citation (DUC) for aggressiveness in attacking enemy aircraft and air bases, March 5 – April 24, 1944. The group escorted bombers in the first shuttle bombing mission from Britain to Russia on June 21, 1944, supported the airborne invasion of Holland in September, participated in the Battle of the Bulge, December 1944 – January 1945, and covered the airborne assault across the Rhine in March 1945. The 4th claimed 583 enemy planes shot