Atomic Annie firing the first atomic artillery shell, 1953

The development of nuclear artillery was part of a broader push by nuclear weapon countries to develop nuclear weapons that could be used strategically against enemy forces in the region (as in strategic use against cities, military bases and heavy industry). Unlike the). Nuclear artillery was developed and deployed by a small group of states including the United States, the USSR, and France.

The Picatinny Arsenal was tasked with building a nuclear-capable artillery piece in 1949. Robert Schwartz, the engineer who designed the initial designs, came up with a design that borrowed heavily from the German's Krpp-built K5 11-inch railway cannons, but was modified to be carried on the roads by a pair of giant tractors. can be carried.

The gun, labeled the M65, is about 84 feet long (26 m) long and 83-tonne in total weight, being the largest road-mobile artillery the US has ever produced. The 38.5-foot-long barrel (12 m) had a 280 mm bore, which was about 11 in.

The gun was given the nickname Atomic Annie (probably derived from the nickname "Anzio Annie" given to the German K5 gun, which was employed against American landings in Italy.)

The design was approved by the Pentagon. Three years' development effort followed. The project progressed rapidly to produce a demonstration model to attend Dwight Eisenhower's inaugural parade in January 1953.

Grable's explosion occurred 19 seconds after its firing. It was 6.25 miles (more than 10 km) away from the gun from which it was fired. The explosion was a burst of air 160 m (524 ft) above the ground, 26 m (87 ft) to the west and 41 m (136 ft) south (slightly upward) of its target.

Its yield was estimated at 15 kilotons, around the same level as Little Boy. An odd feature of the eruption was the formation of a precursor, which was a second shock before the event wave.

This precursor was formed when the shock wave reflected off the ground and crossed the incident wave and Mach stem due to the warm ground air layer and low burst height.

The Gol (W9 warhead) was 11 inches wide (28 cm), 55 inches long (138 cm) and weighed 803 pounds (365 kg). It used 110 pounds (50 kg) of enriched weapons grade uranium, arranged in an advanced ring and bullet system, which collided during firing and set the device on a 15-kiloton chain reaction until it hit the target. was.

The W9 units, which were retired in 1957, were recycled in the low-yield T-4 nuclear demolition wars. These were the first (semi) human-portable nuclear weapons.

After successful testing, at least 20 cannons were manufactured at the Watervliet and Watertown Arsenals, each costing $800,000. They were stationed overseas in Europe and Korea, often being moved constantly to avoid being detected and targeted by opposing forces.

Due to the size of the mechanisms, their limited range, the development of nuclear shells compatible with existing artillery pieces (W48 for 155 mm and W33 for 203 mm), and the development of rocket and missile-based nuclear artillery, the M65 deployed it. It was effectively obsolete soon after. However, it remained a prestige weapon and was not retired until 1963.