M114 155 mm howitzer

Development

Early development

After the end of the First World War a board later named the Westervelt Board after its president, Brigadier General William I. Westervelt, was convened to assess the artillery experience of the combatant powers and map out future directions for the US Army artillery. The conclusion of the board vis-a-vis corps (heavy field) artillery was that an ideal heavy howitzer should have range of at least 16,000 yards and allow the elevation of 65° (as opposed to the existing World War I-era M-1918 155 mm howitzers, a license-built French Canon de 155 C modèle 1917 Schneider, 11.5 km and +42° 20' respectively). Board also recommended that the new 155-mm howitzer and the new 4.7 in gun share all the carriage, even if it compromises both designs.

The M1920 carriage resulting from this requirements was of the split-trail type with pneumatic equilibrators, permitting a total traverse of 60°. Unfortunately, it "gave considerable trouble due to the persistent failure of the top carriage" on the firing tests. In 1923–1925 the design was modified with the top carriage reinforced, with the result standardized as M1925. However, it was never built in steel, because after the evaluation of a wooden model the project was abandoned. Instead, two new carriages were developed and built in the following years, which were designated T1 (photos) and T1E1. All of them had the same ballistics (perhaps even the same gun body), with maximal range of 16,390 yds, and were undergoing tests in the early 1930s. By 1934, the US Army was concerned about the arising high-speed towing requirements not satisfied by the plain bearings and solid rubber ties.

Before and during World War II

In 1939 the development began anew, it was standardized on 15 May 1941 as Howitzer M1 on the Carriage M1. The howitzer itself differed from the older model by a lengthened barrel of 20 calibers and a new breech mechanism. Uniquely it was the sole 'slow-cone' interrupted screw mechanism to enter US service after 1920.

The carriage was also used by the 4.5-inch gun M1. It went through a number of minor changes over time. The original Warner electric brakes were replaced by Westinghouse air brakes on the M1A1. Both the M1 and M1A1 carriages used a mid-axle firing pedestal that was extended by a ratchet mechanism. The M1A2 replaced the ratchet with a screw-jack system and also modified the traveling lock. The M1A1E1 carriage was intended for use in jungle and muddy terrain and replaced the wheels of the M1A1 with a free-wheeling tracked suspension, but the project was terminated after V-J Day without having reached production. The T-9 and T-10 carriages were projects using low-grade steel alloys that were canceled when no longer needed. The T-16 was a light-weight carriage using high-grade steel that was estimated to save some 1200 lb; work began in July 1945 and continued after the war, although nothing seems to have come from it.

Post World War II

After World War II, the production of M1 howitzers continued to 1953. Additionally it was redesignated as the Howitzer, Medium, Towed: 155 mm, M114, with the complete system composed of the cannon (M1), carriage (M1A1), and recoil system (M6, M6A1, M6B1 or M6B2).

A mid-1960s carriage variant was the 155mm XM123 & M123A1 auxiliary-propelled howitzers. The XM123 was produced by American Machine and Foundry and outfitted with two 20 horsepower air-cooled engines produced by Consolidated Diesel Corporation, driver's seat, steering wheel, and guide wheel on the left trail, allowing it to be more rapidly emplaced when detached from the prime mover, while the XM123A1 provided a single 20 horsepower motor with electric steering. The extra weight on the left trail displaced the howitzer after each round was fired, requiring it to be realigned, and the project was abandoned. The concept was copied from the Soviet 85mm SD-44 auxiliary-propelled anti-tank gun developed in 1954 and used by airborne forces (VDV).

Post war variants

• M114A1 − Identical to the M114, but with a M1A2 carriage.
• M114A2 − Similar to the M114A1, but with a slightly longer barrel. Its main distinguishing feature is a groove cut around the barrel about 50-70 mm from the end. The bore of the M114A2 have a 1 in 20 twist instead of the 1 in 12 used in earlier models, extending the range of the projectiles. In 1997, the United States supplied Bosnia-Herzegovina with 116 ex-US Army M114A2s while an additional 145 were earmarked for spare parts.
• M114/39 (Netherlands) − Dutch modernization by RDM Technology, it features a 155 mm 39 caliber barrel supplied by Bofors (now BAE Systems) amongst other upgrades. 96 M114s were modernized for Denmark, 82 for the Netherlands, and 48 for Norway.
• M114/39 (France) − French modernization package by Giat Industries, it included the installation of a 155 mm 39 caliber barrel. It was never sold.
• M114S − Israeli modernization package by Soltam Systems, the M114S features a 155 mm 33 caliber barrel, allowing a standard 155 mm M107 HE projectile to be fired to a maximum distance of 18,300 m; a muzzle brake in the barrel, a pneumatic ramming system for the loader, improved mounts and fixtures, and an optional telescopic sight for direct fire. One prototype was built, but wasn't adopted by the Israeli Defense Forces or exported.
• KM114A1 - Reverse engineered version of the M114A1 by South Korea. It is modified to fire RAP ammunition at a maximum range of 19.5 km. Produced since the late 1970s until the introduction of the KH179.
• 155 mm Howitzer M65 − Yugoslav copy of the M114A1, which was also used by the Yugoslav People's Army. Its virtually identical to the original, with a few minor differences. The M65 fires the standard American M107 HE shell. For training the M65 can be fitted with a 20 mm sub-caliber barrel insert. It was built only in small numbers.

Variants

• Gun variants:

  • M1920 − Prototype.
  • M1925 − First standardized variant. Unbuilt prototype, only exist as a wooden model.
  • T1, T1E1 (1930s) − Prototype.
  • M1 (1941) − First variant to went into production. Barrel lengthened by 20 calibers, new breech mechanism.

• Carriage variants:

  • M1920 − Prototype.
  • M1925 − First standardized variant. Unbuilt prototype, only exist as a wooden model.
  • T1, T1E1 (1930s) − Prototype.
  • M1 (1941) − Split trail carriage, pneumatic tires, mid-axle firing pedestal extended by a ratchet mechanism.
  • M1A1 − M1 with electric brakes replaced with air brakes.
    • M1A1E1 − Intended for use in jungle and muddy terrain, wheels replaced with a free-wheeling tracked suspension. Project terminated without reaching production.
  • M1A2 − M1 / M1A1 with the ratchet mechanism replaced by a screw-jack system, modified traveling lock.
  • T-9, T-10 − Projects using low-grade steel alloys. Canceled.
  • T-16 − Light-weight carriage using high-grade steel. Canceled.

Self-propelled mounts

The howitzer was experimentally mounted on a lengthened chassis of the M5 light tank. The resulting vehicle received the designation 155 mm Howitzer Motor Carriage T64. A single prototype was built before the T64 project was abandoned in favor of T64E1, based on the M24 Chaffee light tank chassis. This was eventually adopted as the M41 Howitzer Motor Carriage and saw action in the Korean War. Towards the end of the Korean War the US Army replaced the M41 self-propelled howitzer with the M44 self-propelled howitzer.

Ammunition

The gun fires separate-loading, bagged charge ammunition, with up to seven different propelling charges, from 1 (the smallest) to 7 (the largest). Muzzle velocity, range and penetration in the tables below are for maximum charge in form of complete M4A1 propelling charge.

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:

Operators

Current

• − 6 as of 2024, used by the Marines
• − 81 used by the Army as of 2024
• − 12
• − 12 as of 2024
• − 230 as of 2024
• − 70 as of 2024, some were upgraded to the HM-41 standard
• − 18 as of 2024
• − 12 as of 2024
• − 20 as of 2024
• − 144 as of 2024
• − 36 as of 2024
• − 10 M114 and Soltam M-68 as of 2024
• − 24 M114A1 as of 2024
• − 50 as of 2024
• − 250 as of 2024, produced under license as the T-65
• − 12 M114A1 as of 2024
• − 517 M114A1/A2 as of 2024
• − 8 M114A1 as of 2024
• − 12 M114A1 as of 2024

Potential

• − In March 2024, it was reported that Greece was negotiating with the Czech Republic a possible transfer of 70 ex-Hellenic Army M114A1s to Ukraine

Former

• − 24
• − 119 M114A2
• • phased out in the Brazilian Marine Corps by 2025
• − 10
• − 57
• − M65
• Croatian Republic of Herzeg-Bosnia − M65
• Denmark − 96 M114/39
• Ethiopian Empire − 12
• − 100
• Imperial State of Iran − 100
• Israel − 50
• Italy
• Japan − 220 total, a small number were produced domestically as Type 58. All retired.
• − First received in September 1951, 294 M1 howitzers were in service by the end of the Korean War. Also produced reverse engineered version of M114A1 as KM114A1 between the late 1970s to early 1980s.
• − 18
• Libya − 20
• − M114A1 and M65
• Norway − 48 M114/39
• Netherlands − at least 144 M114A1 of which 82 were modernized to M114/39
• Republika Srpska Republika Srpska − M65
• − M114A1 and M65
• State Flag of Serbian Krajina (1991).svg Serbian Krajina− M65
• − 16
• − 6
• Spain − 52
• − 48 in storage as of 2024
• United States
• South Vietnam − 100
• North Yemen − 12
• − 12
• FR Yugoslavia − M114A1 and M65
• − M114A1 and M65 used. Passed on to successor states

References

Bibliography

References

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2. B. P. Joyce, New "Four-Point-Seven" Guns [https://tradocfcoeccafcoepfwprod.blob.core.usgovcloudapi.net/fires-bulletin-archive/1922/JAN_FEB_1922/JAN_FEB_1922_FULL_EDITION.pdf The Field Artillery Journal (volume XII) 1922], p. 3 Retrieved 12/14/2023.
3. https://tradocfcoeccafcoepfwprod.blob.core.usgovcloudapi.net/fires-bulletin-archive/1931/NOV_DEC_1931/NOV_DEC_1931_FULL_EDITION.pdf, pp. 30-32 Retrieved 12/14/2023.
4. Okla.), Field Artillery School (Fort Sill. (17 May 1934). "Materiel (Weapons).". Printing plant, The Field artillery school.
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9. Hunnicutt, p 337–339, 502.
10. ''TM 9-1331B, 155mm Howitzer M1 and Mount M14'', p 205-219.
11. Hunnicutt - ''Stuart: A History of the American Light Tank'', p 502.
12. "Εξοπλισμός Εθνικής Φρουράς (Κύπρος)".
13. Zoria, Yuri. (2024-03-15). "Greece negotiates deal with Czechia for ammunition transfer to Ukraine".
14. Moralez, João Paulo. (2025). "O Corpo de Fuzileiros Navais da Marinha do Brasil".
15. Wiener, Friedrich. (1987). "The armies of the NATO nations: Organization, concept of war, weapons and equipment". Herold Publishers.
16. "Arms transfer database". Stockholm International Peace Research Institute.
17. "155 mm Howitzer M1". Gallery Rightwing.