Atomic artillery was a staple in the United States deterrence doctrine since the early 1950s. Guns and howitzers of various calibers and carriages were developed with the added mission of delivering atomic payloads throughout the Cold War. These ranged from the 155 mm W33 shell in the M110 and M115 howitzers to the 406 mm W23 shell on the Iowa class of Battleships. All of these shells were produced and in use at one time or another between 1953 and 1992.

The first of these weapons was conceived during and shortly after World War II. The American T1 240 mm Gun, sometimes referred to as the Black Dragon, was the large artillery system in the Allied inventory that was pitted against the German Krupp K5 240 mm gun in the Italian theater. The notoriety of the Leopold gun was so renowned in the Anzio theater that the gun was called Anzio Annie by the Allies.[1] It was discovered after capture that one of the things that made the system so effective was its carriage.

The Americans subsequently reverse-engineered this carriage and affixed it to a 240 mm tube. The original T72 carriage married to the T1 gun resulted in what was temporarily referred to as the M1 gun. Shortly thereafter the T131 280 mm tube was added, and the development of the W9 & W19 atomic shells made the system even more deadly. Thus Atomic Annie had been born through the marriage of both the T72 and the T131 (plus the M249 and M250 prime movers).

Subsequent developments on the carriage lead to the T76E1 Triple Threat Weapons carriage which replaced the original T72 and T131 with smaller 240, 203, and 175 mm guns (the 175 mm gun temporarily used the T145 carriage).[2] Today, only seven M65’s remain, including the one gun at Rock Island Arsenal. The only complete M65 is in Petersburg, Virginia—with
the Grable shot Annie (the only one to fire an atomic shell) at Fort Sill.

Atomic artillery was also produced for the M109, M110, M114, M115, and M198 howitzers. All of these shells had a maximum yield of around 25 KT, or approximately 1.2 times the power of the Fat Man bomb that was dropped on Nagasaki. These weapons were to be used not only as deterrence, but as countermeasures to prevent or block passage of an enemy into a DMZ or green zone. The idea was that radiation would keep the enemy at bay. The main concentration of these weapons was in Europe and Korea, with the last atomic shell taken out of activity in 1992 after the fall of the Soviet Union.