M3 Gun Motor Carriage

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75 mm Gun Motor Carriage M3
75mm M3 GMC.jpg
A picture of the M3 Gun Motor Carriage
Type Tank destroyer
Place of origin United States
Production history
Designer Ordnance Department
Designed 1940–41
Manufacturer Autocar
Produced 1942–43
Number built 2,116
Weight 20,000 lb (9.1 t)
Length 20.46 ft (6.24 m)
Width 6.45 ft (1.97 m)
Height 8.17 ft (2.49 m) (including gun shield)
Crew 5 (commander, gunner, two loaders, and a driver)

Armor 0.25–0.625 in (6.4–15.9 mm)
1 × 75 mm (3.0 in) M1897A4
Engine White 160AX, 386 in3 (6,330 cc), 6-cylinder, compression ratio: 6.44:1
147 hp (110 kW)
Power/weight 14.7 hp/ton
Transmission Constant mesh
Suspension Semi-ellipitical longitudal leaf spring for wheels and vertical volute springs for tracks
Ground clearance 11.2 in (280 mm)
Fuel capacity 60 US gal (230 l)
150 mi (240 km)

The M3 Gun Motor Carriage (GMC) was a United States Army tank destroyer equipped with one 75 mm M1897A4 gun based on a M3 Half-track chassis. After the fall of France, the U.S. Army decided to make a self-propelled artillery piece from the M1897A4 gun on the M3 chassis, which was designated the T12. After some improvement, it came into production as the M3 Gun Motor Carriage. However, the supply of M2A3 gun shields was insufficient for production needs, so a new gun shield was used. This was designated the M3A1 GMC.

The T12/M3 first served in the Philippines Campaign in 1942. It served with the Provisional Field Artillery Regiment in the anti-tank and the fire-support role. It then served in North Africa in "tank destroyer battalions". It was used ineffectively in the Battle of Kasserine Pass and a few others, but was used with success in the Battle of El Guettar. It also served in the Allied invasion of Sicily, but were eventually superseded by the M10 tank destroyer. A total of 1,361 were converted back into M3A1 half-tracks.

The M3 GMC also served in the Pacific theater, starting with the Battle of Saipan. It proved effective against the Japanese Type 95 Ha-Go and Type 97 Chi-Ha tanks. It later served in the Battle of Okinawa and the Battle of Peleliu and many other island battles.


The M3 GMC was 20.46 feet (6.24 m) long, 6.45 feet (1.97 m) wide, 8.17 feet (2.49 m) high (including the gun shield), and weighed 20,000 pounds (9.1 t). Its suspension consisted semi-elliptical longitudal leaf springs for the wheels and vertical volute springs for the tracks, its transmission consisted of constant mesh, and its ground clearance is 11.2 inches (280 mm).[1][2]

It had a White 160AX 147 horsepower (110 kW), 386 cubic inch (6,330 cc),[3] 6-cylinder with a compression ratio of 6.44:1. It had a 150 mile (240 km) range,[4] 60 US gal (230 l) fuel tank, and a power to weight ratio of 14.7 hp per ton. It was armed with one 75 mm M1897A4, had 0.25–0.625 in (6.4–15.9 mm), and a crew of five (commander, gunner, two loaders, and a driver).[1][2]


After the fall of France, the U.S. Army studied the German's effectiveness against French and British forces. By 1941, there was little available that could be used for self-propelled artillery. The Army had a number of M1897A4 guns, sufficient enough for the mass-production for such a weapon, and the M3 Half-track was coming into production. After some debate, the Army decided to place M1897A4 guns on the M3 half-track chassis,[5] which was designated the T12 GMC.[6]

A batch of 36 T12s were used for testing, while another 50 were quickly thrown into action in the Philippines.[7] The 36 T12s were improved. The improvements included the addition of a mount that raised the gun shield, the replacement of the original gun shield with the M2A3 gun shield, and the addition of a 0.5 in (13 mm) M2 Browning machine gun, which was later removed. After the final improvements were finished, the pilot vehicles were sent to the Autocar Company for production.[6][8]


However, the existing supply of M2A3 gun shields was not sufficient to produce the requirements for the production of the M3. The Ordnance Department came up with a solution, which was to replace the M2A3 with the M2A2 gun shield. The new design was designated as the M3A1 Gun Motor Carriage.[7][9][10]

American use[edit]

The T12/M3 GMC first served in the Philippines in 1941–42, six months after it was designed. Three battalions of the Provisional Field Artillery Brigade operated T12s. It mainly provided direct cover fire and anti-tank support. The Japanese captured a few vehicles and used them in the defense of the Philippines.[7]

By 1942, M3 GMCs became part of "tank destroyer" battalions, which consisted of 36 M3s and four 37 mm M6 GMCs. The M3 GMCs, which were designed to be effective in ambushing tanks, proved to be ineffective in the battles of Sidi Bou Zid and Kasserine Pass, mainly due to poor tactics. Nevertheless, the M3 was later used in the Battle of El Guettar with success, claiming 30 German tanks, including possibly two Tiger tanks, at the cost of 21 M3s. Some M3s also saw service in Operation Husky, but by that time, the M10 tank destroyer had replaced it in the U.S. Army.[11] A total of 1,360 M3 GMCs were also converted back into M3A1 half-tracks.[12][13]

The M3 remained in service with the U.S. Marines and was first used in the invasion of Saipan. It proved highly effective against the Type 95 Ha-Go and the Type 97 Chi-Ha, in the fight against the Japanese 9th Tank Regiment on Saipan. It also served in the Battle of Peleliu and the Battle of Okinawa, and many other conflicts in the Pacific.[14]

Allied use[edit]

Two M3 GMCs used for indirect fire in Italy, 18 February 1945. One of the M3s is named "Acorn Inn".

The M3 GMCs was not supplied to many countries through Lend-lease. A small batch of 170 vehicles were supplied to Britain, which used them in "armoured car" regiments. They were first used in the Tunisian Campaign with the Royal Dragoons. They were also used in Sicily, Italy, and later in France, but were gradually retired. The Free French Army also used M3s for training before receiving M10 GMCs.[14]

See also[edit]



  1. ^ a b Hunnicutt, p. 218.
  2. ^ a b Ness, p. 204.
  3. ^ Hogg & Weeks, p. 94.
  4. ^ Berndt (1993), p. 152.
  5. ^ Hunnicutt, p. 97.
  6. ^ a b Zaloga, p. 22
  7. ^ a b c Zaloga, p. 33.
  8. ^ Hunnicutt, pp. 98–99.
  9. ^ Hunnicutt, p. 104.
  10. ^ Berndt (1994), p. 31.
  11. ^ Mesko, p. 22.
  12. ^ Zaloga, pp. 34–35.
  13. ^ Mesko, p. 21.
  14. ^ a b Zaloga, p. 35.


  • Berndt, Thomas (1993). Standard Catalog of U.S. Military Vehicles. Iola, WI: Krause Publications. ISBN 0-87341-223-0
  • Berndt, Thomas (1994). American Tanks of World War II. Minnesota, MN: MBI Publishing Company. ISBN 0-87938-930-3
  • Hogg, Ian V.; Weeks, John S. (1980). The Illustrated Encyclopedia of Military Vehicles. Englewood Cliffs, NJ: Prentice-Hall. ISBN 0-13-450817-3
  • Hunnicutt, R. P. (2001) Half-Track: A History of American Semi-Tracked Vehicles. Navato, CA: Presido Press. ISBN 0-89141-742-7
  • Mesko, Jim (1996). M3 Half-tracks in Action. Carrollton, TX: Squadron/Signal Publications. ISBN 0-89747-363-9
  • Ness, Leland S. (2002). Jane's World War II Tanks and Fighting Vehicles. New York, NY: HarperCollins. ISBN 0-00-711228-9
  • Zaloga, Steven J. (1994). M3 Infantry Half-track 1940–1973, Oxford: Osprey Publications. ISBN 1-85532-467-9

External links[edit]