Born out of a United States Navy (USN) requirement for a carrier-based, tactical, nuclear strike aircraft and designed under the supervision of the Douglas Aircraft Company's Edward H.Heinemann, the Skyhawk went on to become one of the USN and United States Marine Corps (USMC) iconic aircraft of the Vietnam War. Based around Heinemann's concept of 'keep it light, keep it simple' the Skyhawk evolved from a light-weight nuclear strike aircraft to an aircraft capable of hauling large amounts of ordnance by comparison to its size and with it a proven ability to accept damage and survive. It also served in the training, carrier qualification, 'buddy' tanker and target facilities roles. Originally designated A4D under the USN's designation system, but better know from 1961 as the A-4, the Skyhawk was built in large numbers at Douglas' and later McDonnell Douglas' factories at El Segundo and Long Beach.