F-4 Phantom II Vietnam WarUSAF F 4 Phantom Vietnam War airplane model. The Phantom II was developed initially as a twin engined two seat long range all weather attack fighter for service with the US Navy. A letter of intent to order two prototypes was issued 18 October 1954, at which time the aircraft was designated AH 1. The designation was changed to F4H 1 26 May 1955, with change of mission to missile fighter, and the prototype XF4H 1 flew for the first time 27 May 1958.