M101 howitzer

The 105 mm M2A1 (M101A1) howitzer was the standard light field howitzer for the United States in World War II, seeing action in both the European and Pacific theaters. Entering production in 1941, it quickly entered the war against the Imperial Japanese Army in the Pacific, where it gained a reputation for its accuracy and powerful punch. The M101A1 fired 105 mm high explosive (HE) semi-fixed ammunition and had a range of 11,270 meters, or 12,325 yards, making it suitable for supporting infantry.

Widespread usage
All of these qualities of the weapon, along with its widespread production, led to its adoption by many countries after the war. Its ammunition type also became the standard for many foreign countries' later models. In 1962, the artillery designation system was changed and the 105mm M2A1 howitzer became the M101A1. It continued to see service in the Korean and Vietnam Wars. Though a similar model, the M102 howitzer, shared the same roles in battle, it never fully replaced the M101A1. Today, the M101A1 has been retired by the U.S. military, though it continues to see service with many other countries.

The Canadian Forces continued to use the M2A1 as the C1 Howitzer until 1997, when a modification was made to extend its service life; it is now designated the C3. The changes include a longer barrel, a muzzle brake, reinforced trails and the removal of shield flaps. It remains the standard light howitzer of Canadian Forces Reserve units. The C3 is used by Reserve units in Glacier National Park in British Columbia as a means of avalanche control. In addition, the M101 has found a second use in the U.S. as an avalanche control gun, supervised by the US Forest Service.

France and the State of Vietnam used it during the First Indochina War.

A number of M2/M101 howitzers were used by the Socialist Federal Republic of Yugoslavia and approximately 50 were inherited by Croatia, of which 4 are still in use for training with the Croatian army.

M2 Howitzers are still in limited service in the Australian Army Reserve, but are being replaced with 81mm mortars with an emphasis on the retention of indirect fire support skills. In regular service they were replaced by the 105mm L119 Hamel gun and the 155mm M198 howitzers.

Two M2 howitzers (1942) are still employed in providing the gun salute at Kristiansten Fortress, in Trondheim, Norway.

Operators

 * 🇩🇴 Dominican Republic
 * Iraqi Kurdistan
 * 🇱🇧 Lebanon
 * South Vietnam
 * 🇩🇴 Dominican Republic
 * Iraqi Kurdistan
 * 🇱🇧 Lebanon
 * South Vietnam
 * 🇩🇴 Dominican Republic
 * Iraqi Kurdistan
 * 🇱🇧 Lebanon
 * South Vietnam
 * 🇩🇴 Dominican Republic
 * Iraqi Kurdistan
 * 🇱🇧 Lebanon
 * South Vietnam
 * 🇩🇴 Dominican Republic
 * Iraqi Kurdistan
 * 🇱🇧 Lebanon
 * South Vietnam
 * Iraqi Kurdistan
 * 🇱🇧 Lebanon
 * South Vietnam
 * Iraqi Kurdistan
 * 🇱🇧 Lebanon
 * South Vietnam
 * Iraqi Kurdistan
 * 🇱🇧 Lebanon
 * South Vietnam
 * 🇱🇧 Lebanon
 * South Vietnam
 * South Vietnam
 * South Vietnam
 * South Vietnam
 * South Vietnam
 * South Vietnam
 * South Vietnam
 * South Vietnam
 * South Vietnam
 * South Vietnam
 * South Vietnam
 * South Vietnam
 * South Vietnam
 * South Vietnam
 * South Vietnam
 * South Vietnam
 * South Vietnam
 * South Vietnam
 * South Vietnam
 * South Vietnam
 * South Vietnam
 * South Vietnam

Variants
Gun variants: Carriage variants:
 * M1920 - prototype.
 * M1925E - prototype.
 * T2, standardized as M1.
 * M2 (1934) - minor changes to the chamber to allow use of fixed ammunition.
 * M2A1 (1940) - modified breech ring.
 * M3 - lightweight howitzer, with barrel shortened by 27 inches.
 * T8, standardized as M4 - vehicle-mounted variant with modified breech and with cylindrical recoil surface.
 * M101 - post-war designation of M2A1 on carriage M2A1
 * M101A1 - post-war designation of M2A1 on carriage M2A2
 * C3 - Canadian C1 (M2A1) with lengthened, 33-caliber barrel
 * M1920E - prototype, split trail.
 * M1921E - prototype, box trail.
 * M1925E - prototype, box trail.
 * T2, standardized as M1 - split trail, wooden wheels.
 * M1A1 - M1 carriages rebuilt with new wheels, brakes and other parts.
 * T3 - prototype.
 * T4 - prototype.
 * T5, standardized as M2 (1940) - split trail, steel wheels with pneumatic tires.
 * M2A1 - electric brakes removed.
 * M2A2 - modified shield.
 * XM124 & XM124E1 Light Auxiliary Propelled Howitzer - prototype (1962-1965) - produced by Sundstrand Aviation Corporation, who added an auxiliary drive system for local maneuverability (See also similar XM123 Medium Auxiliary Propelled 155mm Howitzer with similar configuration). The base XM124 provided two 20 horsepower, air-cooled engines, while the XM124E1 provided a single 20 horsepower engine and electric steering.
 * M2A2 Terra Star Auxiliary Propelled Howitzer - prototype (1969-1977) - Lockheed Aircraft Service Company added an auxiliary drive system and a tri-star wheel system to the carriage of an M2A2 105mm Light Howitzer to provide local maneuverability. The last surviving example is at the Rock Island Arsenal Museum.



Self-propelled mounts

 * Medium Tank M4A4E1 - M2A1 in mount T70.
 * Medium Tank M4(105), M4A3(105) - M4 in mount M52.
 * Medium/Heavy Tank M45 - M4 in mount M71.
 * Experimental mount on Holt tractor - M1920.
 * Experimental chassis designed by J Walter Christie - M1920.
 * 105mm Howitzer Motor Carriage T9 (based on Cletrac MG-2 tractor).
 * 105mm Howitzer Motor Carriage T19 (based on M3 halftrack) - M2A1.
 * 105mm Howitzer Motor Carriage T32 / M7 - M2A1.
 * 105mm Howitzer Motor Carriage T76 / M37 (Light Tank M24 chassis) - M4 in mount M5.
 * 105mm Howitzer Motor Carriage T88 (76mm GMC M18 chassis) - M4 in mount M20.
 * M56 105mm similar to the M101 made in ex Yugoslavia and still made in Bosnia
 * EVO-105 105mm howitzer mounted on an armored 5-ton truck system built by Samsung Techwin for the Republic of Korea Army

Ammunition
The gun fired semi-fixed ammunition, with 105mm Cartridge Case M14. The propelling charge consisted of a base charge and six increments, forming seven charges from 1 (the smallest) to 7 (the largest). Use of M1 HE rounds prepared for the 105mm howitzer M3 (same projectile and cartridge, but different propelling charge) was authorized.

HEAT M67 Shell was originally designed as fixed round, with Cartridge Case M14 type II. It was later changed to semi-fixed type with the standard cartridge, but with non-adjustable propelling charge. For blank ammunition, a shorter Cartridge Case M15 with black powder charge was used.