When the United States Navy (USN) set out to replace the piston-engined World War II-era A-1 Skyraider, the new attack aircraft needed to be all-weather and carrier-based. In 1957, the contract was awarded to Grumman, and the twin-engined A-6 Intruder was developed. The prototype made its first flight on April 19, 1960. The Intruder's career began in 1963 and would carry on for 34 more years. The A-6 was capable of low-level flying in all weather conditions, and its wings were very efficient at subsonic speeds. The aircraft's large, blunt nose and slender tail earned it a string of nicknames, including Double Ugly, The Mighty Alpha Six, Iron Tadpol, Drumstick and Pregnant Guppy.
The Intruder was redesignated A-6A in the fall of 1962 and entered squadron service in February 1963. The A-6 became the Navy's and Marine Corps' principal medium and all-weather/night attack aircraft from the mid-1960s until the 1990s. The Intruder first saw combat during the Vietnam War, where it was used extensively against targets in Vietnam. The aircraft's ability to fly in any weather condition, long range and heavy payload of 8,170 kg made it invaluable during the war. However, its effectiveness in flying low and delivering its payload made it especially vulnerable to anti-aircraft fire. In the eight years that the A-6 was used during the war, the USN and USMC (United States Marine Corps) lost 84 aircraft to all causes. Ten were shot down by surface-to-air missiles, 2 were destroyed by Red Chinese Shenyang J-6s, 16 were lost to operational causes, and the remaining 56 were lost to conventional ground fire and anti-aircraft artillery.