The Mark 23 was a further development of the Army's Mk-9 & Mk-19 280mm artillery shell. This was a 15-20 kiloton nuclear warhead adapted to a 16 in naval shell used on the 4 Iowa Class Battleships. While the USN had capable aircraft and missiles to use in the delivery of nuclear weapons, their thought was that the Mk 23/Mark 7 16in/50caliber cannon combination was extremely accurate and usable in any weather condition compared to early jet aircraft and missile technology. 50 weapons were produced starting in 1956 but shortly after their introduction the four Iowa's were mothballed. The weapon stayed in the nuclear inventory until October 1962. There is no known case of the weapon ever being deployed to an operational battleship.
Specifications
L: 5.3ft, W: 1,900lbs,
Performance
Range: Based on 23 mile range of a 2,700lb shell
Yield: 15-20 Kilotons.
This in theory would give each Iowa class Battleship capable of delivering 135-180 kilotons worth of explosives in one salvo. An unique capability that would have proved decisive in any conflict on sea or on land. The nuclear tests with the Mk-9 (11in Army shell) had the shell detonated as an aerial burst. The nuclear tests at the ABLE detonation showed an air burst detonation did little structural damage to battleships. It is unknown from the material I have read if the Mk-23 was designed to detonate on impact or under water which would most likely cause an explosion much like the BAKER nuclear test that caused considerably more damaged to the test fleet. Even with a single air burst detonation a Mk 23, it would have damaged or destroyed much of the enemy battleship fragile equipment it would need to fight if they survived the explosion. Thus leaving for any of the Iowa's easy pickings with their conventional 16in shells.
