105mm Howitzer M2

The 105mm Howitzer M2A1 was the main divisional artillery piece used by the US Army during the Second World War, equipping an impressive 264 field artillery battalions, as well as serving with the US Marine Corps. It still remained in service as late as 2021 in South Korea.

The Westervelt Board of 1919 had recommended the use of the 105mm howitzer as the main divisional weapon of the US army, replacing the lighter 75mm guns. However the board also acknowledged that this would be expensive, so suggesting at least using it to replace the Schneider 155mm howitzer in one artillery battalion per division.

Work on the new weapon began in the 1920s, and in December 1927 the 105mm Howitzer M1 on Carriage M1 was standardized. This had a split trail, and was designed so it wouldn’t need a firing pit when used at its highest angles. This was done by placing the centre of gravity of the barrel in front of the mount, and balancing it with springs. It had hydro-pneumatic recoil and a horizontal sliding breech. Although this version of the weapon was standardised it didn’t enter production, and instead the army used a mix of 75mm and 155mm guns.

In the early 1930s the Ordnance Department developed a new T1 cartridge case. This required a change to the chamber of the howitzer, and in April 1934 the modified weapon was standardized as the 105mm Howitzer M2 on Carriage M1 (keeping the carriage from the Howitzer M1). This version kept the wooden spoked wheels of the Howitzer M1. In the early 1930s 14 105mm howitzers were built, part of a wider plan to build 75, enough to equip three artillery regiments. It isn’t clear if these howitzers were the M1 or the M2. They were tested in 1932, and performed acceptably, but these were the only examples of the 105mm howitzer built before the outbreak of the Second World War.

At the same time as the howitzer was being modified, plans were in place to update the carriage to allow it to be towed by motor vehicles. This work was originally meant to begin in 1933, but didn’t get started until 1936. In February 1938 two new carriages - the T3 and T4 - were delivered to the Aberdeen Proving Grounds. The T4 was lighter and was considered to be better for motor transport, but not quite good enough. As a result two new designs, the T4E1 and T5 were submitted for trials in November 1939. The T5 was chosen, and was standardised as the M2 carriage on 23 February 1940. By then a first batch of 48 M2 Howitzers on T5 Carriage had already been ordered.

As the howitzer was being modified to fit the new carriage, a series of minor modifications were made, including some to the breech ring. In March 1940 this version was standardized as the 105mm Howitzer M2A1 on Carriage M2. This was the version that entered full scale production, and the Howitzer M2A1 became the standard version throughout the Second World War. A total of 8,536 Howitzer M2A1s were produced during the war - 597 in 1941, 3,325 in 1942, 2,684 in 1943, 1,200 in 1944 and 730 in 1945

The M2A1 had a horizontal sliding breech block. The barrel was carried on a cradle on a recoil sleigh that was wrapped round the barrel. The recuperator cylinder was carried above the barrel. The equilibrator assembly linked the axle area to the rear of the cradle.  The trunnions were mounted close to the breech, to allow the gun to fire at high elevations without needing a pit to be dug to take the recoil. The gun could fire HE, HEAT, WP Smoke, BE Smoke, BE coloured smoke, chemical, canister and shaped charge shells.

The shells were semi-fixed. They were fed into the gun as a single piece, but the cartridge could be dismantled to adjust the amount of propellant being used. Each shell carried a seven-part charge, with each part in a cloth bag. One was fixed to the base of the case, but the other six could be removed to reduce the shell’s range.

When it entered production in 1940 only two shells were produced – the standard HE shell and a WP smoke shell. In 1941 a base ejection smoke shell was added, copied from a British 25-pounder shell. Later came a shaped charge anti-tank shell, coloured smoke shells and a canister shot round.

A number of changes were made to the carriage. In November 1942 the War Department decided that towed vehicles under 5,000lb weight didn’t need power operated brakes that could be controlled from the prime mover. These were deleted from the Carriage M2 to produce the Carriage M2A1 of May 1943.

In August 1942 General McNair of Army Ground Forces asked for better shields on field artillery. The new M2A3 was given an auxiliary splinter shield in front of the main shield, to provide more cover when the gun was elevated, and an enclosed screw traverse system was used. It was standardized in August 1943 and a program was put in place to convert older carriages to the M2A3 standard. 

A number of experimental designs were produced. The Carriage M2E1 had a box trail carriage similar to that of the British 25-pounder, but was cancelled in September 1943. The M2E2 had folding spaces like the German lFH 18 105mm howitzer. The M2A1E1 had a muzzle brake on the barrel.

The 105mm Howitzer M2 was produced in very large numbers, with 8,536 built during the Second World War. The US Army adopted it as the standard divisional artillery gun, replacing the 75mm gun in three artillery battalions in each division. The 105mm howitzer was to be used for direct support, while the larger 155mm howitzer was used for general support.

During the Second World War the 105mm equipped 264 field artillery battalions, including 147 divisional battalions and 14 non-divisional battalions in the European Theatre and 62 divisional and 9 non-divisional battalions in the Pacific.

The Marines started to use it in 1942. Each division began with one of its four artillery battalions using the 105mm howitzer. By the invasions of Saipan and Guam that had risen to two out of four and by Iwo Jima it had risen to three out of four.

A large number of M2A1s were give away under lend lease. Britain only received 16, but 476 went to China, 239 to France and 223 to various countries in Latin America.

Production of the M2 continued after the Second World War, and by the time it stopped in 1953 a total of 10,202 had been built. In 1962 it was redesignated as the M101A1. It was used during the Korean and Vietnam Wars, but after that was replaced by the 105mm howitzer M102

Elsewhere the M2 remained in service for even longer. The Australian Army retired it in 1988, and the Army Reserve in the late 2000s. Canada produced a modified version in the 1950s which remained in use into the early 2000s. It is still in use with the Canadian Reserves and is used on avalanche control duties. France operated the type will into the 1980s. South Korea still operated 2,000 of them in 2021!

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