First tested during The ''Castle Union” Nuclear Test of April, 1954 – The Mark 14 Nuclear Device was the first solid fuel staged Thermonuclear Weapon developed. The Mark 14 is often credited as being the “cause” for the creation of the dreaded “Atomic War Clock”, which is used to express the amount of time needed for a Nuclear War to start. The Mark 14 Device when configured as a Bomb, weighs 30,000-pounds and was “Air Dropped” from Strategic Medium Range Bombers. A Guide Parachute helped to control The Device's descent to the target. The Mark 14 was a timed “Air Burst” Device and was never intended for Ground detonation. Controversial in that The Mark 14 used enriched Lithium Isotope 7, The Device produced great amounts of radiation at a high yield of 50-Megatons. The Mark 14 was classed as part of The RACER IV Class of America's first Tactical Nuclear Weapons developed expressly for use against The Soviet Union. Although not truly known, it is speculated that up to (5) Mark 5 Devices were produced. By 1956, most that been deactivated and incorporated into the newer Mark 17 Devices.