The F3H Demon was the first swept-wing jet fighter designed by McDonnell Aircraft and the only single-engine carrier-based fighter built by the company. In 1956 the F3H-2N Demon was fully qualified as a front-line fighter for the U.S. Navy. The F3H-2M Demon, first flown in 1955, was the first U.S. combat aircraft designed to be armed primarily with missiles rather than guns. McDonnell Aircraft delivered the last of 522 Demons in 1959 and they remained in squadron service until 1964.