Artillery

M101 105 mm Howitzer

Also known as
  • M101A1
  • M-101A1 105mm
  • M101A1 105 mm howitzer
  • M2A1 105 mm howitzer
  • Howitzer, 105 mm, M2A1
  • 105 mm Howitzer M2A1
  • M2A2 105 mm howitzer
  • Howitzer M2A2 on Carriage M2A2
  • M101 105mm towed howitzer
  • M101A1 105mm howitzer
  • 105mm M101/33
  • M101/33
  • M101/M2A1 33-caliber upgrade

The M101 is a U.S.-origin 105 mm towed field howitzer descended from the wartime M2A1, produced at Rock Island Arsenal and exported widely after U.S. service. Its split-trail carriage, semi-fixed 105 mm ammunition family, and later 33-caliber modernization packages kept the gun useful from 1955 Vietnam War fire bases to Philippine urban direct-fire missions and Lithuanian-donated M101A1 guns in Ukrainian service.

M101 105 mm Howitzer, 105 mm towed field howitzer, Artillery
Image source: M101A1 Howitzer Display in ORDC Side View 20121013.jpg

Role in Conflicts

2017 Battle of Marawi
Fire Support
Side
Philippine government forces

Philippine Army M101 105 mm howitzers were reported in direct-fire use against Islamic militants during the 2017 Battle of Marawi, where gunners used 105 mm guns to penetrate reinforced concrete positions.

1955 Vietnam War
Fire Support
Side
United States and South Vietnam

U.S. Army sources describe the M101/M101A1 as the Army's main light artillery system heading into the 1955 Vietnam War and state that the M101 was last used in combat by the U.S. Army during that war.

Profile / Specs

Profile

Origin
United States; supplied to Ukraine from Lithuanian stocks
Type
105 mm towed field howitzer
Service note
World War II-era design still used from allied stocks in the 2014 Russia-Ukraine War
Designer
U.S. Army Ordnance Department
Designed
Interwar development; M2A1 standardized before World War II
Produced
1940-1953
Number built
10,200 Rock Island Arsenal-produced M2A1 howitzers by 1953

Specifications

Caliber
105 mm
Shell
105x372R semi-fixed ammunition
Weight
2,260 kg
Barrel length
2.31 m
Maximum range
11,270 m with standard ammunition; Ultra Defense reports 15,965 yd for M548 projectiles
Rate of fire
Up to 10 rounds per minute; about 3 rounds per minute sustained
Crew
8
Carriage
Single-axle split-trail towed carriage
Elevation and traverse
-5 degrees to +66 degrees elevation; 46 degrees traverse
M101/33 barrel
33-caliber / 3,500 mm upgraded barrel replacing the original short M101/M2A1 barrel
M101/33 range
15 km with HE-ER BT ammunition; 18.1 km with HE-ER BB base-bleed ammunition
Variants

U.S. Army history treats the wartime M2A1, postwar M101, and later M101A1 labels as one closely related 105 mm howitzer family rather than separate unrelated weapons.

VariantConfigurationDesignation notes
M2A1World War II and early postwar designation

The U.S. Army Rock Island article describes the M2A1 as first produced in 1940 and later renamed M101 after World War II.

Sources: RIA Self-Guided Tour: M2A1 105 MM Towed Howitzer

M2A2Postwar cannon/carriage configuration

Ultra Defense describes the M101A1 configuration as using a 105 mm M2A2 howitzer cannon on an M2-series carriage and recoil mechanism.

Sources: M101/M101A1 105 mm Howitzer

M101A11962 redesignation and long-service export label

Army Historical Foundation history states that the M2A1 was redesignated M101A1 in 1962, while later Ukraine and Philippines sources use M101A1/M101 for donated or active-service guns.

Sources: M102 105mm Howitzer, Ukraine army uses old M101A1 105mm howitzers donated by Lithuania to shell Russian troops, Philippine artillery soldiers still training with American WWII-era M101 105mm towed howitzer

M101/3333-caliber modernization package

Yugoimport markets an M101/M2A1 upgrade that replaces the original short barrel with a 33-caliber barrel, adds a double-baffle muzzle brake, and raises range with extended-range 105 mm ammunition.

Sources: Upgrade of 105 mm M101/M2A1 Howitzer, 105mm M101/33

Ammunition Fired

Ultra Defense Corp describes the M101 family as firing standard 105 mm ammunition, including HE, smoke, WP, chemical, practice, and drill cartridge types.

AmmunitionAmmunition typeFiring evidence
Cartridge, 105 mm, High-Explosive, M1, 105 mm semi-fixed high-explosive artillery cartridge for 105 mm howitzers, MunitionsCartridge, 105 mm, High-Explosive, M1105 mm high-explosive cartridge

Ultra Defense lists HE M1 shells among ammunition used by the M101 family, matching the cataloged 105 mm M1 high-explosive cartridge record.

Sources: M101/M101A1 105 mm Howitzer

Cartridge, 105 mm, Smoke, WP, M60, 105 mm white-phosphorus smoke artillery cartridge, MunitionsCartridge, 105 mm, Smoke, WP, M60105 mm smoke and white-phosphorus cartridge

Ultra Defense lists WP M60 and FS M60 smoke shells in the M101 ammunition set, and Army ammunition data sheets identify M2A1/M2A2 M101/M101A1 cannon families with M60-series smoke ammunition.

Sources: M101/M101A1 105 mm Howitzer, TM 43-0001-28 Army Ammunition Data Sheets

Cartridge, 105 mm, Illuminating, M314, 105 mm howitzer-fired illuminating cartridge with parachute-retarded canister, MunitionsCartridge, 105 mm, Illuminating, M314105 mm illuminating cartridge

Army ammunition data sheets list M314-family illuminating cartridges with M2A2/M101/M101A1 105 mm howitzers among compatible firing weapons.

Sources: TM 43-0001-28 Army Ammunition Data Sheets

Designation And Ammunition Notes

The designation history and ammunition set are best read together: several sources use M2A1, M101, and M101A1 for the same U.S. 105 mm howitzer lineage, while ammunition records describe the semi-fixed 105 mm cartridges that kept the family useful across many operators.

Designation chain

M2A1 was the wartime designation. U.S. Army history says the weapon was renamed M101 after World War II, while Army Historical Foundation history records M101A1 as the 1962 designation.

Production center

Rock Island Arsenal manufactured key recoil and carriage assemblies, and Army Historical Foundation history records 10,200 Rock Island-produced M2A1s by 1953.

Operator reach

U.S. Army Rock Island history describes the M101 as exported to 70 additional operators, and Ultra Defense describes at least 67 purchasing countries.

U.S. retirement

The U.S. Army retired the M101 by 1989 during the M119 transition, but the same Army history notes limited U.S. avalanche-control use after military retirement.

M101/33 upgrade

Yugoimport's M101/M2A1 package replaces the original barrel with a 33-caliber tube, adds a double-baffle muzzle brake, and retains the basic howitzer structure and recoil system.

Ammunition family

Ultra Defense lists HE, HEAT, smoke, WP, chemical, practice, and drill ammunition categories for the M101 family, including M1 HE and M60-series smoke shells.

This supports compatibility context for cataloged 105 mm cartridge records without implying independent conflict-use evidence for every cartridge.

Sources: RIA Self-Guided Tour: M2A1 105 MM Towed Howitzer; M102 105mm Howitzer; M101/M101A1 105 mm Howitzer; Upgrade of 105 mm M101/M2A1 Howitzer.

Timeline

M101 105 mm Howitzer Key Events

  1. M2A1 production begins

    U.S. Army Rock Island history states that the M2A1 was first produced in 1940 and that Rock Island Arsenal manufactured the weapon's recoil mechanism and carriage.

    Sources: RIA Self-Guided Tour: M2A1 105 MM Towed Howitzer

  2. Rock Island production era ends

    The Army Historical Foundation records 10,200 Rock Island-produced M2A1 howitzers by the time production ended in 1953.

    Sources: M102 105mm Howitzer

  3. M101A1 designation adopted

    Army Historical Foundation history states that the M2A1 was redesignated M101A1 in 1962 as the older light howitzer entered the Vietnam era.

    Sources: M102 105mm Howitzer

  4. U.S. Army retirement

    U.S. Army Rock Island history states that the United States retired its M101 inventory by 1989 as the M119 105 mm howitzer entered service, while some guns remained in limited avalanche-control use.

    Sources: RIA Self-Guided Tour: M2A1 105 MM Towed Howitzer

  5. 105 mm guns used in Marawi

    2017 Battle of Marawi studies describe Philippine gunners using 105 mm guns in direct fire against reinforced urban positions during the battle.

    Sources: The 2017 Battle of Marawi: Small Team Lessons Learned for the Close Fight

  6. Lithuania says 105 mm howitzers are en route to Ukraine

    Lithuania's Ministry of National Defence said at the Ramstein-format donor meeting that Lithuanian 105 mm howitzers were on the way to Ukraine.

    Sources: We cannot afford pauses, Ukraine needs a continuous supply of arms

  7. Lithuania reports 18 transferred 105 mm howitzers

    Lithuania's Ministry of National Defence reported that its military aid to Ukraine included 18 units of 105 mm howitzers.

    Sources: Annual Lithuania contribution to Ukraine fight for freedom

Media

M101 105 mm Howitzer Videos

M101 105 mm Howitzer Images

M101 105 mm Howitzer, 105 mm towed field howitzer, Artillery - view 1
Source: M101-105mm-howitzer-4.jpg
M101 105 mm Howitzer, 105 mm towed field howitzer, Artillery - view 2
Source: M101 105 mm howitzer in Lithuanian service.jpg
Related Weapon Systems
M119, 105 mm lightweight towed howitzer, ArtilleryArtilleryM119105 mm lightweight towed howitzerThe M119 is the U.S. 105 mm lightweight towed howitzer derived from the British L119 light gun and built around air-mobile infantry fire support. The M119A3 variant adds digital fire control, self-location, and communications upgrades while retaining a light carriage that can be moved by trucks, cargo aircraft, or helicopter. U.S. Army sources place the type in Gulf War, Iraq War, and Afghanistan service, and Ukrainian forces later received American 105 mm howitzers during the 2014 Russia-Ukraine War.
M198 155 mm howitzer, 155 mm towed howitzer, ArtilleryArtilleryM198 155 mm howitzer155 mm towed howitzerThe M198 is a U.S.-designed 155 mm towed howitzer developed at Rock Island Arsenal to replace older M114-series guns. Its split-trail carriage, nine-person crew, air-transportable layout, and 22-30 km range made it a standard U.S. Army and Marine Corps fire-support weapon before the lighter M777 replaced it in U.S. service. Direct conflict sourcing now traces M198 fielding from Desert Storm through U.S. use in Afghanistan and Iraq, Islamic State capture and cross-border use in Iraq and Syria, Iraq-aligned militia firing, and coalition-backed Iraqi Army live-fire training.

Sources

M101/M101A1 105 mm HowitzerPublisher: Ultra Defense Corp | Note: Supports system background, ammunition, production history, and technical specifications. | Accessed: 2026-07-07M101 American 105mm Towed HowitzerPublisher: U.S. Army TRADOC ODIN | Note: Supports general identification and core specifications for the M101 105 mm towed howitzer. | Accessed: 2026-07-07RIA Self-Guided Tour: M2A1 105 MM Towed HowitzerPublisher: U.S. Army | Note: Supports M2A1/M101 designation history, Rock Island Arsenal production context, retirement by the M119 transition, ammunition-family background, and direct 1955 Vietnam War combat-use context for the M101. | Accessed: 2026-07-07M102 105mm HowitzerPublisher: The Army Historical Foundation | Note: Supports M2A1/M101A1 redesignation history, Rock Island Arsenal production quantity and 1953 production endpoint, M101A1 specifications, and direct 1955 Vietnam War context as the Army's main light artillery system heading into the war. | Accessed: 2026-07-07TM 43-0001-28 Army Ammunition Data SheetsPublisher: U.S. Army | Note: Supports the M60-series 105 mm smoke/WP ammunition relationship by listing M2A1/M2A2, identified with M101/M101A1 cannon families, in the associated 105 mm howitzer ammunition context. | Accessed: 2026-07-07Upgrade of 105 mm M101/M2A1 HowitzerPublisher: Yugoimport-SDPR | Note: Supports the M101/M2A1 33-caliber modernization package, double-baffle muzzle brake, retained recoil system, upgrade-kit weight, and extended-range ammunition claims. | Accessed: 2026-07-07105mm M101/33Publisher: WeaponSystems.net | Note: Supports the M101/33 designation as an upgrade of existing M101 howitzers with a longer 33-caliber ordnance. | Accessed: 2026-07-07Lithuania Sent Another Batch of Military Aid to UkrainePublisher: Defense Express | Note: Corroborates Lithuanian transfer of 105 mm howitzers to Ukraine, but does not independently identify them as M101A1. | Accessed: 2026-07-07We cannot afford pauses, Ukraine needs a continuous supply of armsPublisher: Ministry of National Defence of the Republic of Lithuania | Note: Officially corroborates that Lithuanian 105 mm howitzers were on the way to Ukraine in September 2022, but does not independently identify them as M101A1. | Accessed: 2026-07-07Annual Lithuania contribution to Ukraine fight for freedomPublisher: Ministry of National Defence of the Republic of Lithuania | Note: Officially corroborates Lithuania's transfer of 18 units of 105 mm howitzers to Ukraine, but does not independently identify them as M101A1. | Accessed: 2026-07-07Ukraine army uses old M101A1 105mm howitzers donated by Lithuania to shell Russian troopsPublisher: Army Recognition | Note: Supports direct 2014 Russia-Ukraine War use of Lithuanian-donated M101A1 howitzers by Ukrainian forces. | Accessed: 2026-07-07Philippine artillery soldiers still training with American WWII-era M101 105mm towed howitzerPublisher: Army Recognition | Note: Supports Philippine Army M101 direct-fire use against Islamic militants during the 2017 Battle of Marawi. | Accessed: 2026-07-07The 2017 Battle of Marawi: Small Team Lessons Learned for the Close FightPublisher: The Cove | Note: Supports 2017 Battle of Marawi direct-fire context: Filipino gunners used 105 mm guns in direct fire to penetrate thick concrete walls, but the article does not identify the guns as M101. | Accessed: 2026-07-07M101A1 Howitzer Display in ORDC Side View 20121013.jpgPublisher: Wikimedia Commons | Note: Image provenance and licensing for the primary M101A1 howitzer image; file page lists CC BY-SA 3.0 and GFDL licensing options. | Accessed: 2026-07-07M101-105mm-howitzer-4.jpgPublisher: Wikimedia Commons | Note: Image provenance and licensing for the secondary M101 gallery image; file page lists Creative Commons Attribution 3.0 licensing. | Accessed: 2026-07-07M101 105 mm howitzer in Lithuanian service.jpgPublisher: Wikimedia Commons | Note: Image provenance for a Lithuanian-service M101 105 mm howitzer; file page lists MoD Lithuania authorship context, GNU Free Documentation License terms, and VRT-confirmed reuse permission. | Accessed: 2026-07-07