With the conflict in Vietnam escalating, the Blackhorse Regiment was alerted for assignment to Southeast Asia on 11 March 1966. The Regiment began specialized training for combat in a counterinsurgency environment. Modifications were made to the organization and equipment (MTOE) with emphasis on the use of modified M113 armored personnel carriers (APCs). Two M-60 machineguns with protective gun shield were mounted at the rear of the vehicle and a gun shield was added around the .50 caliber machine gun located at the commander's hatch. This lethal combination produced a deadly M-113 that was swiftly maneuverable and armor protected. Its nickname was ACAV (Armored Cavalry Assault Vehicle).
The Regiment's modifications emphasized the use of ACAVs instead of the main battle tanks and the M-114s that were found in reconnaissance platoons. The tank companies, with their M-48A3 main battle tanks, remained the same in each squadron.
The Blackhorse Regiment arrived in Vung Tau, South Vietnam on 7 September 1966 and was commanded by Col. William W. Cobb. Operation Hickory (7 - 15 October 1966) produced the first enemy casualties inflicted by the 3rd Squadron and elements of the 919th Engineer Company in the vicinity of Phu Hoa.
Blackhorse Base Camp
"Atlanta" was the code name for the establishment of Blackhorse Base Camp - the new home of the 11th Armored Cavalry Regiment in Vietnam. Blackhorse Base Camp was located approximately 6 kilometres (3.7 mi) south of the village of Xuan Loc on Route 2 and approximately 2 kilometres (1.2 mi) southeast of the village of Long Goia. Saigon is approximately 35 kilometres (22 mi) to the west along Rt. 1. The operation began on 20 Oct. and concluded on 3 Nov. 1966.
Stanton's Vietnam Order Of Battle lists the following locations for the 11th Armored Cavalry Regiment's Headquarters in Vietnam:
Bien Hoa Sept. 66 - Nov. 66 Long Binh Dec. 66 - Feb. 67 Xuan Loc March 67 - Jan. 69 Lai Khe Feb. 69 Long Giao March 69 - Sept. 69 Bien Hoa Oct. 69 - June 70 Di An July 70 - March 71
Operation Cedar Falls
From January until 18 May 1967 the Regiment conducted three major search and destroy operations. These operations would later be known as reconnaissance in force (RIF) operations. The first of these operations commence on 8 Jan. 1967 and was known as "Operation Cedar Falls". It continued until 24 Jan. 1967. The 1st and 2nd Squadrons operated in the infamous "Iron Triangle" region near Ben Cat employing search and destroy tactics, screening and blocking, and security in attacks on successive objectives.
Operation Junction City
Operation Junction City I and II involved the 1st and 3rd Squadrons. It began on 18 Feb. 1967 and ran through 15 April 1967. This operation took these squadrons to the headquarters of the Central Office South Vietnam (COSVN) believed to be located in Binh Duong Province with the objective of destroying this important headquarters. This joint mission conducted with the 1st Australian Task Force secured lines of communication and fire support bases (FSB). Extensive RIF operations were conducted as well.
Commencing on 23 April 1967 the third operation titled Operation Manhattan was a thrust into the Long Nguyen Secret Zone by the 1st and 2nd Squadrons. This zone was a long suspected regional headquarter of the Viet Cong. 60 tunnel complexes were uncovered. 1884 fortifications were destroyed. 621 tons of rice was evacuated during these operations. The 11th Armored Cavalry Regiment was building a solid reputation for carrying out effective reconnaissance in force operations. Operation Manhattan ended on 11 May 1967.
Beginning on April 1967 and running through 21 March 1968, the Regiment was tasked to secure and pacify Long Khánh District. This year long mission was called Operation Kittyhawk. It achieved three objectives: Viet Cong (VC) were kept from interfering with travel on the main roads, Vietnamese were provided medical treatment in civic action programs like MEDCAP and DENTCAP and finally, RIF operations were employed to keep the VC off balance, making it impossible for them to mount offensive operations.
From the summer of 1967 until the winter the Regiment was led by Col. Roy W. Farley. Operation Emporia I & II was a road clearing operation with limited RIF missions by the 1st and 3rd Squadrons in Long Khánh District. Operation Valdosta I & II was a regimental size operation. Its purpose was to provide security at polling places during elections and to maintain reaction forces to counter VC agitation. So successful was this operation that 84.7 % of eligible voters cast ballots in Long Khánh District in the first general election and 78 % in the second.
This operation involved the 1st and 2nd Squadrons of the 11th Armored Cavalry. Its purpose was to secure routes that moved logistical personnel of the 101st Airborne Division between Binh Long and Tay Ninh Provinces. Cordon, search and RIF missions were also performed.
Operation Fargo ran from 21 Dec. 1967 until 21 Jan 1968. This regimental size operation conducted RIFs in Binh Long and Tay Ninh Provinces and opened Route 13 to military traffic for the very first time.
The Tet Offensive
The early part of 1968 was marked by the most ambitious and embolden offensive attack coordinated by the VC and NVA in the history of the war. The Tet Offensive was designed to coincide with the Vietnamese New Year.
This operation began on 31 Jan. 1968. Word was received by the II Field Force HQs to immediately re-deploy to the Long Binh/Bien Hoa area to relieve installations threatened by the Tet Offensive. At 1400 hours (2:00 pm) the 1st Squadron was called to move from their position south of the Michelin Rubber Plantation to the II Field Force Headquarters. The 2nd Squadron moved from north of the plantation to III Corps POW Compound were enemy soldiers were sure to attempt to liberate the camp. The 3rd Squadron moved from An Loc to III Corps Army, Republic of Vietnam (ARVN) Headquarters. It took only 14 hours and 80 miles to arrive in position after first being alerted.
Operation Alcorn Cove
The security operation in the Long Binh/Bien Hoa area and the area around Blackhorse Base Camp by the 1st and 2nd Squadrons is continue under Operation Alcorn Cove which began on 22 March 1968. This joint mission with the ARVN 18th Division and 25th Division was a twofold operation of security and RIFs. Operation Toan Thang was an extension of "Alcorn Cove". That joint operation involved the 1st and 25th Infantry Divisions.
"Workhorse" The 3rd Squadron
K Troop was part of the 3rd Squadron and known as "Killing K Troop". 3rd Squadron's nickname was, fittingly, "Workhorse". Shortly after its arrival in Vietnam, the 3rd Squadron engaged the Viet Cong for the first time. 3rd Squadron inflicted such devastating casualties on the enemy that it was awarded a Meritorious Unit Citation for this period.
The Tet Offensive of 1968 gave the squadron a chance to fight the enemy's troop formations in open combat. In Bien Hoa the 3rd Squadron drove the enemy forces from the area near III Corps Headquarters. Its action was crucial in smashing the enemy's offensive.
On October 20, 2009 President Barack Obama presented a Presidential Unit Citation to veterans of Troop A of the regiment for their heroism along the Cambodian border on March 26, 1970.