M65 Atomic Cannon

M65 atomic cannon
Surviving 240mm prototype at the Virginia War Museum
Type	Towed artillery
Place of origin	United States
Specifications
Weight	83.3 tons (gun and carriage)
Length	84 feet (26 m)
Width	16.1 feet (4.9 m)
Height	12.2 feet (3.7 m)
Crew	5–7
Caliber	280 mm
Effective firing range	approximately 20 miles (30 km)

The M65 atomic cannon, often called "Atomic Annie", was a towed artillery piece built by the United States and capable of firing a nuclear device. It was developed in the early 1950s, at the beginning of the Cold War, and fielded, by 1953, in Europe and South Korea.

Picatinny Arsenal was tasked to create a nuclear capable artillery piece in 1949. Robert Schwartz, the engineer who created the preliminary designs, essentially scaled up the 240mm shell (then the maximum in the arsenal) and used the German K5 railroad gun as a point of departure for the carriage. (The name "Atomic Annie" likely derives from the nickname "Anzio Annie" given to a pair of German K5 guns which were employed against the American landings in Italy.) The design was approved by the Pentagon, largely through the intervention of Samuel Feltman, chief of the ballistics section of the ordnance department's research and development division. A three-year developmental effort followed. The project proceeded quickly enough to produce a demonstration model to participate in Dwight Eisenhower's inaugural parade in January 1953.

The cannon was transported by two specially designed tractors, both capable of independent steering in the manner of some extra-long fire trucks. Each of the tractors was rated at 375 hp, and the somewhat awkward combination could achieve speeds of 35 miles an hour and negotiate right angle turns on 28 ft wide, paved or packed roads. The artillery piece could be unlimbered in 15 minutes, then returned to traveling configuration in another 15 minutes.

On May 25, 1953 at 8:30am, the atomic cannon was tested at the Nevada Test Site (specifically Frenchman Flat) as part of the Upshot–Knothole series of nuclear tests. The test — codenamed "Grable" — was attended by the Chairman of the Joint Chiefs of Staff, Admiral Arthur W. Radford and Secretary of Defense Charles Erwin Wilson; it resulted in the successful detonation of a 15 kt shell (W9 warhead) at a range of seven miles. This was the first and only nuclear shell to be fired from a cannon (the Little Feller 1 test shot of an M388 used a Davy Crockett weapon system which was a recoilless smooth bore gun firing the warhead mounted on the end of a spigot inserted in the barrel of the weapon.)