M115 howitzer

The M115 203 mm howitzer, also known as the M115 8 inch howitzer, was a towed howitzer used by the United States Army. Until the 1950s it was designated the 8 inch Howitzer M1. The original design started in 1919 but lapsed until resurrected in 1927 as a partner-piece for a new 155 mm gun. It was standardised as 8 inch Howitzer M1 in 1940. The M115/M1 was towed by the M35 Prime Mover gun tractor or a Mack 7⅓ ton 6x6 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. It consists of equilibrator assemblies, elevating and traversing mechanisms, two single-wheel, single-axle heavy limber, two-axle bogie with eight tyres and two trails. Four spades, carried on the trails, are used to emplace the weapon. The British 8 inch howitzer was produced in both England and under license in the US for the American Expeditionary Forces in Europe during World War I as the 8-inch Howitzer MK. VI. It was in service with the US Army till replaced by the M115. There are no reports of the MK. VI or another marks being used during World War II.

The first photos of the M115 type 8 inch cannon on its redesign carriage appeared in 1931, but development was slowed by the Great Depression.

The M115 saw service in World War II, the Korean War, the Vietnam War, the Second Taiwan Strait Crisis, and the Croatian War of Independence. In the late 1950s it was adopted in small numbers by several NATO armies to fire the W33 (M454 shell) and later the W79 nuclear artillery shell under the NATO nuclear sharing concept, a role which ended when the smallest types of tactical nuclear weapons were removed from service and eliminated.

Operators

 * 🇮🇹 - 9° Gr.A.Pe. - Gruppo Artiglieria Pesante "Rovigo", 1° Gr.A.Pe. - Gruppo Artiglieria Pesante "Adige", Gruppo A.U.C.-T.M. - Allievi Ufficiali di Complemento a Traino Meccanico
 * - former operator - 24 systems,
 * 🇵🇰 - About 28 in service
 * - Many on DMZ
 * - former operator 1953-1992, 12 systems
 * - İn Turkey - 60
 * 🇵🇰 - About 28 in service
 * - Many on DMZ
 * - former operator 1953-1992, 12 systems
 * - İn Turkey - 60
 * - former operator 1953-1992, 12 systems
 * - İn Turkey - 60

Self-propelling mounts

 * The howitzer was mounted on a modified M4 medium tank chassis, in mount M17. The resulting vehicle was initially designated 8 inch Howitzer Motor Carriage T89 and eventually standardized as 8 inch Howitzer Motor Carriage M43. A total of 48 units were built.
 * 8 inch Howitzer Motor Carriage T80 - based on T23 Medium Tank chassis, never advenced past proposal stage.
 * 8 inch Howitzer Motor Carriage T84 - based on T26 Medium Tank chassis, a single pilot was built in 1945.
 * The howitzer was mounted on a purpose-built tracked chassis to become the 8 inch Self-Propelled Howitzer M110. Notably accuracy and rate of fire suffered from having to lower the weapon to use the track mounted auto loader.

Ammunition
The howitzer fired separate loading, bagged charge ammunition, with seven different propelling charges, from 1 (the smallest) to 7 (the largest). The M454 Nuclear shell had its own M80 cartridge with three propelling charges.