The P-51 Mustang was a World War II American long-range fighter and fighter-bomber designed by North American Aviation. The aircraft entered service as a long-range escort fighter in the middle of the war. The P-51 Mustang was a solution to the need for an effective bomber escort. It used a common, reliable engine and had internal space for a larger-than-average fuel load. With external fuel tanks, it could accompany the bombers from England to Germany and back.