The United States has a long history of developing light tanks, balancing mobility, firepower, and protection to meet specific battlefield needs. Among these, the M551 Sheridan stands out as an experimental yet influential design from the Cold War era.
Fast forward to today, and the United States Army has identified a need for a similar, relatively lightweight armor platform.
M551 Sheridan
The M551 Sheridan, introduced in the late 1960s, was designed to provide airborne and armored reconnaissance units with a highly mobile anti-tank weapon.
Tipping the scales at just over 15 tons, the Sheridan made extensive use of aluminum to keep its weight low, with the advantage of allowing it to be air-dropped from transport aircraft and maneuver more effectively in rough terrain thanks to a good power-to-weight ratio.
Its main armament, the 152mm M81 gun launcher, was theoretically capable of firing both conventional explosive shells as well as the MGM-51 Shillelagh guided missile, an early guided anti-tank missile developed in response to the rapid increase in armor following the Second World War.
However, the Shillelagh had significant shortcomings.
“The Shillelagh, however, did present problems. It was significantly larger than conventional rounds, so only a small number could be carried. In addition, the Shillelagh had a minimum range of 2,400 feet—the missile had to be 2,400 feet away from the tank before the gunner could start tracking it,” the Army Historical Foundation explains.
“The M81’s M409 HEAT rounds had a maximum range of 2,000 feet, leaving the Sheridan with [a] “dead zone” between 2,000 and 2,400 feet. When the crew fired the main gun, the recoil would often knock out the missile launcher’s electronics.
The only other Army tank to use the Shillelagh would be M60A2, and eventually, none of the missiles were ever fired in anger.”
Its aluminum armor provided the M551 Sheridan scant protection against enemy fire, proving vulnerable to even machine gun fire and mines. In addition, the 152mm gun launcher, though innovative, suffered from reliability issues.
Recoil from the main gun also put undue stress on the Sheridan. However, it did see some service in Vietnam, and afterward, it was gradually phased out without a direct replacement.
A Return to the Past with M10 Booker
Today, the United States Army fields the M10 Booker, which, though similar in weight to the Vietnam-era Sheridan, serves a fundamentally different purpose.
The U.S. Army officially categorized the M10 as a Mobile Protected Firepower vehicle rather than a light tank.
Instead, the Booker is designed to offer infantry units with direct fire support instead of serving as a dedicated anti-tank platform.
The M10 Booker Combat Vehicle proudly displays its namesake on the gun tube during the Army Birthday Festival at the National Museum of the U.S. Army, June 10, 2023. The M10 Booker Combat Vehicle is named after two American service members: Pvt. Robert D. Booker, who posthumously received the Medal of Honor for actions in World War II, and Staff Sgt. Stevon A. Booker, who posthumously received the Distinguished Service Cross for actions during Operation Iraqi Freedom. Their stories and actions articulate the Army’s need for the M10 Booker Combat Vehicle, an infantry assault vehicle that will provide protection and lethality to destroy threats like the ones that took the lives of these two Soldiers. (U.S. Army photo by Bernardo Fuller)
Armed with a 105mm rifled gun, it is meant to engage enemy fortifications, machine gun nests, and lightly armored vehicles—threats that are more pressing and immediate obstacles to infantry operations than main battle tanks.
Unlike the Sheridan, the M10 Booker puts a premium on survivability with improved armor and modern defensive systems, a reflection of past lessons learned in part from the Sheridan.
This shift in focus in modern vehicle design emphasizes that more lightly-armed vehicles like the M10 should support infantry rather than take on main battle tanks.
The shift from the M551 Sheridan to the M10 Booker highlights changing combat needs, technological advancements, and the incorporation of previous lessons learned.
While the Sheridan attempted to give airborne infantry a mobile tank-killing ability, the Booker’s role is centered on supporting infantry with firepower and battering down a variety of obstacles they might face.
About the Author: Caleb Larson
Caleb Larson is an American multiformat journalist based in Berlin, Germany. His work covers the intersection of conflict and society, focusing on American foreign policy and European security. He has reported from Germany, Russia, and the United States. Most recently, he covered the war in Ukraine, reporting extensively on the war’s shifting battle lines from Donbas and writing on the war’s civilian and humanitarian toll. Previously, he worked as a Defense Reporter for POLITICO Europe. You can follow his latest work on X.
