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 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 German K5 gun which was 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 engines. 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.)
After the successful test, there were at least 20 of the cannons manufactured at Watervliet and Watertown Arsenals, at a cost of $800,000 each. They were deployed overseas to Europe and Korea, often continuously shifted around to avoid being detected and targeted by opposing forces. Due to the size of the apparatus, their limited range, the development of nuclear shells compatible with existing artillery pieces (the W48 for the 155mm and the W33 for the 203mm), and the development of rocket and missile based nuclear artillery, the M65 was effectively obsolete soon after it was deployed. However, it remained a prestige weapon and was not retired until 1963.
The kind of monstrous weapons the Cold War spurned is mind boggling.