The 303d Air Expeditionary Group is a provisional United States Air Force unit. In 2011, it was assigned to United States Air Forces Europe to activate or inactivate as needed. The unit was first activated as the 303d Bombardment Group in February 1942. During World War II, the 303d was one of the first VIII Bomber Command B-17 Flying Fortress units in England. The group's "Hell's Angels" was the first B-17 to complete 25 combat missions in June 1943, and the group went on to fly more than 300 combat missions, more than any other B-17 group in the theater. The B-17 "Knock-out Dropper" was the first aircraft in Eighth Air Force to complete 50, then 75 missions. The group was awarded the Distinguished Unit Citation for completing an attack against a heavily defended target in January 1944.