M56 Scorpion

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M56 Scorpion
M56 at AAF Tank Museum.JPG
M56 Scorpion preserved at the American Armored Foundation Tank Museum in Danville, Virginia.
Type Self-propelled gun
Place of origin United States
Service history
Used by See users
Wars Vietnam War, Western Sahara War
Production history
Manufacturer Cadillac Motor Car Division of General Motors
Produced 1953–1959
Weight 7.1 tonnes (16,000 lb)
Length 4.55 metres (14 ft 11 in) (excluding gun)
Width 2.57 metres (8 ft 5 in)
Height 2 metres (6 ft 7 in) over gun shield
Crew 4 (commander, gunner, loader and driver)

Armor unarmored except for blast shield
90 mm M54 Gun
29 rounds
Engine Continental A01-403-5 gasoline engine
200 brake horsepower (150 kW)
Transmission Allison CD-150-4, 2 ranges forward, 1 reverse
Suspension Torsion tube over bar at wheels 1 and 4, torsion bar at wheels 2 and 3
Ground clearance 0.32 m (1 ft 1 in)
Fuel capacity 210 litres (46 imp gal; 55 US gal)
230 kilometres (140 mi)
Speed 45 kilometres per hour (28 mph)

The M56 Scorpion was an American unarmored, airmobile self-propelled anti-tank gun, which was armed with a 90mm M54 gun with a simple blast shield, and an unprotected crew compartment.


The M56 was manufactured from 1953 to 1959 by the Cadillac Motor Car Division of General Motors for use by US airborne forces, though the vehicle was eventually used by the Spanish Navy Marines, Morocco and the Republic of Korea as well. With a crew of four (commander, gunner, loader and driver), the M56 weighed 6.4 tonnes (14,000 lb) empty and 7.7 tonnes (17,000 lb) combat-loaded. It had infrared driving lights but no Nuclear, Biological and Chemical (NBC) protection system and was not amphibious.

The M56 was a fully tracked vehicle with rubber-tired run-flat road wheels and front drive sprocket wheels. It was powered by a Continental A01-403-5 gasoline engine developing 200 brake horsepower (150 kW) at 3,000 rpm, allowing a maximum road speed of 28 miles per hour (45 km/h) and a maximum range of 140 miles (230 km). Twenty-nine rounds of main gun ammunition were carried, and only the blast shield was armored.

In service[edit]

The M56 saw combat service with U.S. forces in the Vietnam War. It was deployed with the 173rd Airborne Brigade, which was the only Airborne Brigade deployed with the M56,[1] where it was used mainly in a direct fire-support role. Its function as an airmobile, self-propelled, anti-tank vehicle was eventually replaced in Vietnam by the troubled but effective M551 Sheridan which had a fully armored turret. The USMC used the Ontos, which had an armored cabin and was armed with recoilless rifles, in a similar role (the running gear of the first Ontos prototype was the same as on the M56, but it was replaced for the production variant).

As for foreign operators, Morocco was only export customer which had used M56 Scorpions in actual combat. M56 Scorpions were deployed against Sahrawi rebels during Western Sahara War.


Map of former M56 operators in red

Former operators[edit]


Diorama of destroyed M56 at the AAF Tank Museum. Note the prominent rubber tires on the road wheels.
  • Ropkey Armor Museum in Crawfordsville, Indiana
  • A well preserved M56 can be found in a city park in Auburn, Washington.
  • Tillicum Park in Forks, Washington.
  • Next to a park in Elmwood Park, New Jersey.
  • A restored M56 is on display at the American Armored Foundation Tank Museum in Danville, Virginia, along with a diorama of a destroyed M56.
  • American Legion post in Duluth, Georgia.
  • Veterans Memorial Stadium in Cedar Rapids, Iowa.
  • 82nd Airborne War Memorial Museum in Fort Bragg, North Carolina.
  • American Legion Post 8 in Guntersville, Alabama.
  • Boyd County War Memorial in Armco Park in Summit, Kentucky.
  • Forest Hill Station in Millersburg, Kentucky.
  • Veterans of Foreign Wars Post 2524 Culpepper, Virginia.
  • Iowa Gold Star Museum at Camp Dodge in Johnston, Iowa.
  • Military Vehicle Technology Foundation's facility in Portola Valley, in California. However, it will soon be relocated to the Collings Foundation in Stow, Massachusetts.
  • 45th Infantry Museum in Oklahoma City, Oklahoma.
  • Fort Sill, Oklahoma
  • American Legion Hall, Post 88, in Donelson, Tennessee.
  • Camp Mabry in Austin, Texas.
  • Combat Air Power Museum at Forbes Field, in Topeka, Kansas.

See also[edit]


  1. ^ Rottman, Gordon L.; Anderson, Duncan (22 April 2008). The US Army in the Vietnam War 1965-73. Bloomsbury USA. ISBN 9781846032394 – via Google Books. 
  • Foss, Christopher F. (1974) [1972]. Jane's Pocket Book of Tanks and Armored Fighting Vehicles. Collier Books. p. 153. LC Control No. 73-15286. 
  • Trewhitt, Philip (1999). Armored Fighting Vehicles. New York, NY: Amber Books. p. 126. ISBN 0-7607-1260-3. 

External links[edit]