The M56 "Scorpion" Self-Propelled Gun is an American unarmored,
airmobile self-propelled tank destroyer
A tank destroyer, tank hunter, tank killer, or self-propelled anti-tank gun is a type of armoured fighting vehicle, armed with a direct fire artillery gun or missile launcher, designed specifically to engage and destroy enemy tanks, often w ...
, which was armed with a
90mm M54 gun with a simple blast shield, and an unprotected crew compartment.
History
The M56 was manufactured from 1953 to 1959 by the
Cadillac
The Cadillac Motor Car Division () is a division of the American automobile manufacturer General Motors (GM) that designs and builds luxury vehicles. Its major markets are the United States, Canada, and China. Cadillac models are distributed ...
Motor Car Division of
General Motors for use by US
airborne forces, though the vehicle was eventually used by the
Spanish Navy Marines
The Spanish Naval Infantry ( es, Infantería de Marina) is the naval infantry unit of the Spanish Navy () responsible for conducting amphibious warfare by utilizing naval platforms and resources. The Marine Corps is fully integrated into the A ...
,
Morocco
Morocco (),, ) officially the Kingdom of Morocco, is the westernmost country in the Maghreb region of North Africa. It overlooks the Mediterranean Sea to the north and the Atlantic Ocean to the west, and has land borders with Algeria ...
and
South Korea
South Korea, officially the Republic of Korea (ROK), is a country in East Asia, constituting the southern part of the Korea, Korean Peninsula and sharing a Korean Demilitarized Zone, land border with North Korea. Its western border is formed ...
. With a crew of four (commander, gunner, loader and driver), the M56 weighed empty and combat-loaded. It had
infrared
Infrared (IR), sometimes called infrared light, is electromagnetic radiation (EMR) with wavelengths longer than those of visible light. It is therefore invisible to the human eye. IR is generally understood to encompass wavelengths from aroun ...
driving lights but no
NBC protection
Chemical, biological, radiological and nuclear defence (CBRN defence) are protective measures taken in situations in which chemical, biological, radiological or nuclear warfare (including terrorism) hazards may be present. CBRN defence consis ...
and was not
amphibious
Amphibious means able to use either land or water. In particular it may refer to:
Animals
* Amphibian, a vertebrate animal of the class Amphibia (many of which live on land and breed in water)
* Amphibious caterpillar
* Amphibious fish, a fish ...
.
The M56 was a fully
tracked vehicle with rubber-tired run-flat road wheels and front drive
sprocket
A sprocket, sprocket-wheel or chainwheel is a profiled wheel with teeth that mesh with a chain, track or other perforated or indented material. The name 'sprocket' applies generally to any wheel upon which radial projections engage a chain pass ...
wheels. It was powered by a
Continental
Continental may refer to:
Places
* Continent, the major landmasses of Earth
* Continental, Arizona, a small community in Pima County, Arizona, US
* Continental, Ohio, a small town in Putnam County, US
Arts and entertainment
* ''Continental'' (a ...
A01-403-5
gasoline
Gasoline (; ) or petrol (; ) (see ) is a transparent, petroleum-derived flammable liquid that is used primarily as a fuel in most spark-ignited internal combustion engines (also known as petrol engines). It consists mostly of organic ...
engine
An engine or motor is a machine designed to convert one or more forms of energy into mechanical energy.
Available energy sources include potential energy (e.g. energy of the Earth's gravitational field as exploited in hydroelectric power ...
developing at 3,000 rpm, allowing a maximum road speed of and a maximum range of . Twenty-nine rounds of main gun ammunition were carried, and only the small 5 mm thick blast shield was armored.
In service

The M56 saw combat service with U.S. forces in the
Vietnam War
The Vietnam War (also known by #Names, other names) was a conflict in Vietnam, Laos, and Cambodia from 1 November 1955 to the fall of Saigon on 30 April 1975. It was the second of the Indochina Wars and was officially fought between North Vie ...
. It was deployed with the
173rd Airborne Brigade
The 173rd Airborne Brigade ("Sky Soldiers") is an Airborne forces, airborne infantry brigade combat team (IBCT) of the United States Army based in Vicenza, Italy. It is the United States European Command's conventional airborne strategic respo ...
, which was the only Airborne Brigade deployed with the M56,
where it was used mainly in a direct
fire-support role. Its function as an air-mobile, self-propelled, anti-tank vehicle was eventually replaced in Vietnam by the troubled but effective
M551 Sheridan
The M551 "Sheridan" AR/AAV ( Armored Reconnaissance/Airborne Assault Vehicle) was a light tank developed by the United States and named after General Philip Sheridan, of American Civil War fame. It was designed to be landed by parachute and to sw ...
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 the only export customer which used M56 Scorpions in actual combat. M56 Scorpions were deployed against
Polisario rebels during the
Western Sahara War
The Western Sahara War ( ar, حرب الصحراء الغربية, french: Guerre du Sahara occidental, es, Guerra del Sahara Occidental) was an armed struggle between the Sahrawi indigenous Polisario Front and Morocco from 1975 to 1991 (an ...
. A number of examples were made available to South Korea but not used.
Operators
Former operators
*
*: 5 exported in 1965. Used by
Tercio de Armada from 1966 to 1970
*: 1 for evaluation in 1960
*: 87 received in 1966-1967
*: 60 ex-American M56 were left as surplus but never used
Survivors

United States
*
American Legion Post 8 in Guntersville, Alabama.
*Two of them can be found in the American Military Museum in South El Monte, California.
*American Legion post in Duluth, Georgia.
*
Ropkey Armor Museum
Ropkey Armor Museum (today, known as the Ropkey Armor and Aviation Museum) is a military history museum in Indianapolis, Indiana.
History
The museum is privately owned by the Ropkey family. It stemmed from the founder Fred Ropkey's interest in mi ...
in Crawfordsville, Indiana
*
Veterans Memorial Stadium in Cedar Rapids, Iowa.
*Iowa Gold Star Museum at Camp Dodge in Johnston, Iowa.
*
Combat Air Museum
The Combat Air Museum is a non-profit aviation museum at Topeka Regional Airport (Forbes Field) in Shawnee County, near Topeka, Kansas. The museum is dedicated to the creation of facilities and resources for the education of the local and regiona ...
at the former
Forbes Field
Forbes Field was a baseball park in the Oakland neighborhood of Pittsburgh, Pennsylvania, from 1909 to June 28, 1970. It was the third home of the Pittsburgh Pirates Major League Baseball (MLB) team, and the first home of the Pittsburgh Steelers ...
, in Topeka, Kansas.
*Forest Hill Station in Millersburg, Kentucky.
*Boyd County War Memorial in Armco Park in Summit, Kentucky.
*One can be found in
Constitution Park in
Cumberland, Maryland
Cumberland is a U.S. city in and the county seat of Allegany County, Maryland. It is the primary city of the Cumberland, MD-WV Metropolitan Statistical Area. At the 2020 census, the city had a population of 19,076. Located on the Potomac River, ...
.
*
Military Vehicle Technology Foundation's facility in Portola Valley, in California. However, it will soon be relocated to the
Collings Foundation in Stow, Massachusetts.
*
Elmwood Park,
New Jersey
New Jersey is a U.S. state, state in the Mid-Atlantic States, Mid-Atlantic and Northeastern United States, Northeastern regions of the United States. It is bordered on the north and east by the state of New York (state), New York; on the ea ...
.
*82nd Airborne War Memorial Museum in
Fort Bragg
Fort Bragg is a military installation of the United States Army in North Carolina, and is one of the largest military installations in the world by population, with around 54,000 military personnel. The military reservation is located within C ...
, North Carolina.
*
Fort Sill
Fort Sill is a United States Army post north of Lawton, Oklahoma, about 85 miles (136.8 km) southwest of Oklahoma City. It covers almost .
The fort was first built during the Indian Wars. It is designated as a National Historic Landma ...
, Oklahoma
*45th Infantry Museum in Oklahoma City, Oklahoma.
*One can be found in the city of Elkton, South Dakota on the corner of Elk St. and 3rd St.
*American Legion Hall, Post 88, in Donelson, Tennessee.
*Texas Military Forces Museum,
Camp Mabry
Camp Mabry (ICAO: KATT) is a military installation in Austin, Texas, that houses the headquarters of the Texas Military Department, Texas Military Forces, and Texas Military Forces Museum. Established in 1892, Camp Mabry is the third-oldest activ ...
in Austin, Texas.
*
Veterans of Foreign Wars
The Veterans of Foreign Wars (VFW), formally the Veterans of Foreign Wars of the United States, is an organization of US war veterans, who, as military service members fought in wars, campaigns, and expeditions on foreign land, waters, or ...
Post 2524 Culpeper, Virginia.
*A restored M56 is on display at the American Armored Foundation Tank Museum in
Danville,
Virginia
Virginia, officially the Commonwealth of Virginia, is a state in the Mid-Atlantic and Southeastern regions of the United States, between the East Coast of the United States, Atlantic Coast and the Appalachian Mountains. The geography an ...
, along with a diorama of a destroyed M56.
*A well preserved M56 can be found in a city park in
Auburn, Washington
Auburn is a city in King County, Washington, United States (with a small portion crossing into neighboring Pierce County). The population was 87,256 at the 2020 Census. Auburn is a suburb in the Seattle metropolitan area, and is currently ran ...
.
*Tillicum Park in
Forks, Washington
Forks, also previously known as the unincorporated town of Quillayute, is a city in southwest Clallam County, Washington, United States. The population was 3,335 at the 2020 census. It is named after the forks in the nearby Quillayute, Boga ...
.
* One example can be found outside the Mississippi Armed Forces Museum at
Camp Shelby
Camp Shelby is a military post whose North Gate is located at the southern boundary of Hattiesburg, Mississippi, on United States Highway 49. It is the largest state-owned training site in the nation. During wartime, the camp's mission is to ...
.
South Korea
*One former
Republic of Korea Army
The Republic of Korea Army (ROKA; ko, 대한민국 육군; Hanja: 大韓民國 陸軍; RR: ''Daehanminguk Yuk-gun''), also known as the ROK Army or South Korean Army, is the army of South Korea, responsible for ground-based warfare. It is the l ...
example on display at the
War Memorial of Korea.
See also
*
G-numbers
This is the Group G series List of the United States military vehicles by (Ordnance) supply catalog designation, — ''one'' of the alpha-numeric "Standard Nomenclature Lists" (SNL) that were part of the overall List of the United States Army ...
(SNL G289)
*
M-numbers
The following is a (partial) listing of vehicle model numbers or M-numbers assigned by the United States Army. Some of these designations are also used by other agencies, services, and nationalities, although these various end users usually assig ...
*
FV4401 Contentious
References
;Notes
;Bibliography
*
*
*
External links
90 mm Self-propelled Gun M56 ScorpionAmerican Armored Foundation Tank Museum Website{{Use dmy dates, date=June 2017
Cold War armored fighting vehicles of the United States
Tank destroyers of the United States
Airborne fighting vehicles
Military vehicles introduced in the 1950s