The M115 203 mm howitzer, also known as the M115 8 inch howitzer, was a towed howitzer used by the United States Army. Originally designated the 8 inch Howitzer M1, it was designed during the buildup to World War II as a counterpart to the German 17 cm K18 gun. The M115 could be towed by the M35 Prime Mover gun tractor or a large truck.
The M115 owes some of its origins to the British BL 8 inch Howitzer of the First World War, using the same Welin screw for the breech. The carriage was the same as used for the US 155 mm gun, and was also adopted by the British for their 7.2 inch Mark 6 howitzer
The M115 saw service in World War II, the Korean War, and the Vietnam War. In NATO service, its main purpose was to fire nuclear rounds, which have since been discontinued. The M115 was removed from service due to its short range.
The original short barrel (25 calibres) version was mounted on a tracked chassis to become the 8 inch Self-Propelled Howitzer M110.