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M551 Sheridan: U.S. Airmobile Tanks 1941-2001

by Steven J. Zaloga, Osprey Publishing, 2009

One of the world’s foremost armor experts, Steven Zaloga applies his formidable archives to the American airborne tank in M551 Sheridan. Pursued by Britain and the Soviet Union as well as the United States, fighting vehicles capable of being flown or parachuted to support airborne troops has always been problematical, since adding weight considerations to the factors of armament and armor protection condemns any such weapon to some degree of compromise. And, as Zaloga shows in the few American airborne vehicles to achieve production, the results were disappointing, such as the World War II M22 Locust light tank and the largely open M56 Scorpion self-propelled antitank gun, which saw some service in Vietnam.

A culmination of previous efforts produced the M551 Sheridan, whose air-mobility was made possible by aluminum armor and the innovative MGM-51 Shillelagh 152mm antitank missile. Encouraged by technology-enthralled Secretary of Defense Robert McNamara in spite of numerous development problems and cost overruns, the futuristic looking M551 entered production in 1966 and service in 1968. In January 1969, Sheridans were committed to their first combat assignment: Vietnam, where their Shillelegh missiles were useless. Stripped of some of its superfluous electronics and with added armor on the underside against enemy mines and around the .50-caliber turret machine gun to protect its firer, the Sheridan did prove a bit more than a “$300,000 machine gun platform” when the Army added the hastily developed but devastatingly effective M625 flechette antipersonnel round to its 152mm arsenal. The tank remained highly vulnerable, however, especially to rocket-propelled grenades, and it was never popular with the cavalrymen who made do with it. By the time the U.S. Army withdrew from Vietnam, some 300 had been disabled or damaged, 90 of them total write-offs.

Vietnam saw the most extensive combat use of any American airborne tank, but Zaloga traces the Sheridan’s use thereafter in Panama and the 1991 Gulf War, as well as further attempts to create a successor. Spotty though its fighting record has been, thus far the M551 Sheridan remains about as good as it’s gotten.


Originally published in the August 2009 issue of Vietnam Magazine. To subscribe, click here