Prior to its use of the M198 howitzer of 1979, the United States military (and many of its allies) relied on the World War 2-era M114 towed howitzer to fulfill its 155mm long-range artillery requirement. The weapon served into the Korean War (1950-1953) and across the campaigns of the Vietnam War (1955-1975) before seeing formal retirement with American forces. Design work on the weapon began in 1939 and spanned into 1941 to which the system cleared its requisite trials before being adopted into service. Production spanned from 1941 into 1953 to which some 10,300 units were eventually produced by the Rock Island Arsenal stateside and additional examples appearing under license elsewhere. The M114 still serves in some armies today (2013). Notable current operators include Afghanistan, Argentina, Brazil, Iran, Iraq, South Korea, Lebanon, Pakistan, Philippines, Taiwan, Thailand, Turkey, Venezuela, Vietnam, Indonesia and Malaysia. Notable former operators became Austria, Belgium, Canada, Croatia, Denmark, France, Greece, Israel, Italy, Jordan, Libya, Norway, Netherlands, Portugal, Saudi Arabia, Singapore and Spain (see operators listing below for complete list).
The origin of the M114 actually lay in an initiative by the US Army to design and develop a modern carriage system for its aged M1918 155mm guns. The M1918 was nothing more than a copy of the World War 1-era French Canon de 155 C modele 1917 Schneider system which was procured in number by the American military. When it was decided against modernizing the older M1918 guns in this way, a new gun system was developed as the M1. The carriage became a split trail type and the gun was coupled to a hyrdopneumatic recoil system. The breech incorporated a two-step, "slow-cone" interrupted screw. The gun mounting allowed for an elevation of -2 to +63 degrees and traversal of 25-degrees right or left. The weapon entered production as the 155mm Howitzer M1. It was not until 1962 that the now-modified M1A1 was redesignated to the M114/M114A1.
The M114 was classified as a "medium" artillery piece and was conventional in its overall design and function. The weapon was based around the 155mm gun barrel (M1 or M1A1 series) which sat atop a mounting that also supported the needed M6 series recoil mechanism. The gun barrel lacked a muzzle brake of any sort. The split trail carriage (M1A1 or M1A2 series) closed for transport and opened to support the firing process. The carriage also included a single axle that was double-tired with steel rims and rubber wheels. The system was typically crewed by as many as 11 personnel including the unit commander, gun layer and ammunition handlers. Dimensions included a running length of 24 feet with a width of 8 feet and height of nearly 6 feet. Overall weight was 12,500lb. A trained crew could emplace (make ready to fire) the unit in 5 minutes.
The bread and butter of the M114 was its 155mm shell which came in the following flavors: High-Explosive, Chemical, Illumination and Smoke. The ammunition supply was only limited by the ammunition carrier. Each type was used in accordance to battlefield requirements and the M114 was generally an indirect fire weapon (non line-of-sight) intended to lob shells onto the enemy positions. Muzzle velocity of the HE, chemical and smoke rounds was approximately 1,850 feet per second while the illumination round projected lower at 1,160 feet per second. The HE and chemical rounds also managed the longer engagement range out to 16,355 yards. The Smoke round managed a 9,700 yard range with the illumination round peaking at 7,100 yards. A trained gunnery crew could fire at a rate of 40 rounds per minute sustained. Each projectile was loaded with a bagged charge.
During its storied career, the M114 gave excellent service in its given combat role. As it remains active in several world armies as of this writing (2013), it serves as a testament to its excellent engineering and conventional design. Given its history, the M114 should remain in active service somewhere in the world for the next several decades.