M113 armored cavalry assault vehicles, or ACAVs, and M551 Sheridan light tanks of the 11th Armored Cavalry Regiment plow through rough terrain about a mile and a half from the Cambodian border on March 18, 1970. (AP Photo/Charles Ryan)
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One of the U.S. Army’s specialized units in Vietnam was the 11th Armored Cavalry Regiment, nicknamed the “Blackhorse Regiment.” When deployed in 1966, the regiment was equipped primarily with M113 armored personnel carriers modified with additional guns and shields to become “armored cavalry assault vehicles” for a more offensive role. The ACAV’s basic armament consisted of two 7.62 mm M60 machines guns mounted on either side of the cargo top hatch and a .50-caliber M2 machine gun upfront, protected by a rounded armored collar with armor plates fore and aft to afford more protection for the gunner. Backed by flamethrower-equipped M113s called M132 “Zippos,” M551 Sheridan light tanks and M109 self-propelled howitzers, Blackhorse ACAV crews fought with distinctive aggressiveness in numerous operations in the Saigon area between 1966 and 1972. By mid-1967 mechanized infantry units, which also used M113s, were retrofitting their vehicles to make them similar to ACAVs, but their tactics still differed. Mechanized infantry fought both mounted and dismounted, while the armored cavalry primarily operated mounted and on the move. The Blackhorse Regiment, with three squadrons, was the only full armored cavalry regiment in Vietnam, but most infantry divisions had their own armored cavalry squadrons, adding five to the list: 1st Squadron, 4th Cavalry Regiment, 1st Infantry Division; 1st Squadron, 10th Cavalry, 4th Division; 3rd Squadron, 5th Cavalry, 9th Division; 1st Squadron, 1st Cavalry, 23rd Division (Americal); and 3rd Squadron, 4th Cavalry, 25th Division.
This article appeared in the Autumn 2022 issue of Vietnam magazine.