The Strange Second Life of the M551 Sheridan Light Tank

The M551 Sheridan Light Tank had a checkered career during its service with the United States Army. You can read the details here, but the BLUF is that the M-551 Sheridan was envisioned as a lightweight aluminum, air transportable tank. It was equipped with a massive 152mm short barreled main gun that could fire anti-tank missiles in addition to conventional rounds that could defeat any known armored system at the time. It was a good idea in theory, but that was about as far as it went. The anti-tank missile never proved practical and the cumbersome one piece shells for the 152mm main gun were prone to split in two, spilling large amounts of propellant inside the tank which could lead to an internal explosion. The M551 Sheridan proved invaluable in Vietnam as its light weight allowed it to traverse mud better than most vehicles but suffered from a low rate of fire in combat. This resulted in the M551 Sheridan spending much of its time as a tow truck pulling heavier vehicles out of the mud as the tropical humidity tended to short circuit its electrical firing system.

An M551 Sheridan Light tank preparing to be forward deployed for a live fire exercise in Saudi Arabia during Operation Desert Shield in December 1990. Arrayed around the tank is 20 x 152mm ammunition, 8 x MGM-51 Shillelagh anti-tank missiles, several thousand rounds of .50 cal and 7.62mm machine gun ammunition, 25 gallons of drinking water, three cases of meals ready to eat (MRE) totaling 36 meals for nine days of rations for the crew, two large tarps with framing , and radio gear for establishing a radio post. All of this equipment would be loaded onto the M551 Sheridan light tank before it deployed for combat operations. National Archives photo 6471195

An M551 Sheridan Light tank preparing to be forward deployed for a live fire exercise in Saudi Arabia during Operation Desert Shield in December 1990. Arrayed around the tank is 20 x 152mm ammunition, 8 x MGM-51 Shillelagh anti-tank missiles, several thousand rounds of .50 cal and 7.62mm machine gun ammunition, 25 gallons of drinking water, three cases of meals ready to eat (MRE) totaling 36 meals for nine days of rations for the crew, two large tarps with framing , and radio gear for establishing a radio post. All of this equipment would be loaded onto the M551 Sheridan light tank before it deployed for combat operations. National Archives photo 6471195

After Vietnam, the U.S. Army had large numbers of Sheridan light tanks available that only airborne units wanted. There were proposals to scrap the M551 Sheridan program but cooler heads prevailed and in 1980, the bulk of the M551 Sheridan light tanks were sent to the National Training Center (NTC) at Fort Irwin, California. The NTC was tasked with providing realistic ground training to U.S. Military units that involved simulated tank on tank armored combat in a desert environment. This was an early recognition that many of the U.S. Military’s future battles would be in the Middle East. The M551 Sheridan was an ideal vehicle to form the nucleus of the Soviet opposition force (OPFOR)  and early exercises had the Sheridan’s operating in conjunction with local infantry from Army and United States Marine Corps units to test the combat effectiveness of U.S. and NATO Military units from around the world.

M551 Sheridan light tanks operating in their intended role as an air transportable light tank. Here, two M551 Sheridan light tanks are being airdropped from a C-5 Galaxy transport aircraft. The drop is a two stage process, both stages can be seen in this photo. A Sheridan light tank is in the process of being pulled out of the aircraft by its smaller and stronger deployment parachutes which represents the first stage. The tank already in the air has just separated from its deployment parachutes which deployed much larger second stage descent parachutes which are unfolding in the photo. This two stage process was done to prevent damage to the more delicate descent parachutes as the tank is being pulled out of the aircraft at high speed. National Archives photo 6462244

M551 Sheridan light tanks operating in their intended role as an air transportable light tank. Here, two M551 Sheridan light tanks are being airdropped from a C-5 Galaxy transport aircraft. The drop is a two stage process, both stages can be seen in this photo. A Sheridan light tank is in the process of being pulled out of the aircraft by its smaller and stronger deployment parachutes which represents the first stage. The tank already in the air has just separated from its deployment parachutes which deployed much larger second stage descent parachutes which are unfolding in the photo. This two stage process was done to prevent damage to the more delicate descent parachutes as the tank is being pulled out of the aircraft at high speed. National Archives photo 6462244

One of the early changes made to the M551 Sheridan was to make the tanks look more like the Soviet made equipment that the U.S. Military would encounter in the Middle East. Some of these changes were as simple as replacing the 152mm main gun with a fake barrel to make the vehicle look like a Soviet BMP-1. But other changes were as radical as adding  fiberglass body panels so that a Sheridan light tank looked like a Soviet T-72 main battle tank. Each tank was equipped with sensors to pick up laser signals indicating if the vehicle had been hit by a simulated round. A red light on the tank would light up to indicate a kill.

M551 Sheridan light tanks cross the desert during an Opposing Forces exercise at the National Training Center. The tanks have visual modifications designed to make it resemble Soviet armor.

A group of camouflaged M551 Sheridan’s travel in a convoy at the National Training Center. The lead tank has been mocked up to look like a Soviet BMP-1, the second tank has been concealed to look like a ZSU-23, the remaining tanks have been reworked to look like T-55 and T-72 main battle tanks. National Archive Photo 6425040

The combination of highly experienced Sheridan tank crews with infantry that practiced a radical form of combined arms maneuver warfare shocked many of the early units that went to the National Training Center. Exercises would be repeated until the visiting unit could master the OPFOR and this highly realistic training did much to prepare the U.S. Military for the 1991 Gulf War. The Soldiers and Marines who went to Kuwait and then into Iraq found themselves fighting an enemy less capable than the one they had been fighting in the Mojave desert for the previous decade.

The ultimate evolution of the M551 Sheridan OPFOR aggressor tank at the National Training Center was a highly realistic looking mock up of the Soviet T-72. This tank continued to serve in the aggressor role until 2003, a full 36 years after the Sheridan light tank first went into service. While the Sheridan had limited combat utility for much of its life, the Sheridan will be regarded as one of the most useful post World War II tanks operated by the United States Army. National Archives Photo 6425276

The ultimate evolution of the M551 Sheridan OPFOR aggressor tank at the National Training Center was a highly realistic looking mock up of the Soviet T-72. This tank continued to serve in the aggressor role until 2003, a full 36 years after the Sheridan light tank first went into service. While the Sheridan had limited combat utility for much of its life, the Sheridan will be regarded as one of the most useful post World War II tanks operated by the United States Army. National Archives Photo 6425276

The M551 Sheridan was retired in 2003 from the NTC, but it did get it’s day in the sun. During the 1991 Gulf War, there was concern that the Iraqi Republican Guard would cross the border into Saudi Arabia. This led to a hasty deployment of U.S. Army airborne forces with their Sheridan light tanks which then deployed along the border. The reality was that the M551 Sheridan wouldn’t have fared well against an Iraqi T-72, but that was something the Iraqi Army didn’t know. The sudden appearance of large numbers of American Sheridan light tanks along the Saudi Arabian border was enough to cause the Iraqi Army to pause and gave the Allied coalition enough time to mass sufficient forces in Saudi Arabia to prevent an invasion. For the second time in its career, the M551 Sheridan proved its worth by never firing a shot in anger.

5 Comments

  • Mark T Woolery says:

    Great article Byron. I worked for Philco Ford Aeronutronics at LAMP (Lawndale Army Missile Plant) from 1966 to 1969. We manufactured the
    MGM-51 Shillelagh anti-tank missile and I have many fond memories.

  • Rick Townsend says:

    6/31st Infantry, Ft. Irwin…1985 from paratrooper to armored infantry soviet style. What an awakening. Best experience I had in 26 years in the Army.

  • Sp4 Dunsel says:

    I gunned one at Graf in the late 70’s, with tracks locked that 152 round would rock the Sheridan back til the 2nd to 3rd road wheel would come off the ground, between that and the dust from the blast it could take a good 2-3 seconds to re-acquire the target. I think the only place they were used in anger was Nam, ( if the humidity let the paper cased round fire at all! )

  • bill nichols says:

    Totally concur with Spec Dunsel; one helluva ride when engaging the main gun!

    Dead accurate, though; I blew up a range marker at 300 meters at Bragg in ROTC advanced camp in ’73. The tac really whaled on me: “You missed that dumpster by a good 50 meters!” “Dumpster?” He’d told me, “See that yellow thing at about 300 meters? Hit it.” So I did what he told me. Wasn’t really much he could say. }:)

  • Jim Massa says:

    I was 3rd ACR ft bliss 72/75 in New Mexico Dona Ana tank gunnery driver , loader gunner eventually TC when we taught week end warriors they fired heat round from left side almost turned us over powerful recoil Jim

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