In the early stages of the war it was generally felt that Vietnam was an unsuitable theatre for the employment of armored units. Service in RVN involved considerable revision of doctrine, tactics and equipment. Standard tables of Organisation and Equipment were revised and once in RVN, armored units fell back upon heavily Modified TO&E's to reflect the changing role of armor in this particular theatre.
Their subsequent deployment dispelled this idea. The mobility of armored units made them extremely versatile and in many cases their mobility became a critical factor despite the otherwise overwhelming use of helicopters.
The first US armored unit (3rd Platoon, Company B, 3rd Marine Tank Battalion) arrived in March 1965 but there was little inclination to deploy it due to what was considered unsuitable terrain and the requirement for a large logistical support base. During initial considerations regarding the deployment of the 1st Infantry Division it had been planned to 'leave behind' the divisions two tank battalions and to convert it's mechanized infantry to regular grunts. It was eventually decided that only the divisional cavalry (1st squadron, 4th cavalry) would deploy with it's assigned tanks. The M114's of the 1st squadron were replaced prior to deployment with M113's due to the relatively poor performance of the former which had been used for some time by the ARVN armored forces. Vietnam saw the emergence of the M-113 and variants as the dominant armored vehicle in spite of it's original design conception as a simple armored infantry vehicle.
Unfortunately, despite the lessons learned from WWII and Korea, armored units were still split and parceled out so that 1st squadron was split into troops with one assigned to each brigade thus giving the brigades of the division some mechanized recon capability. General Westmoreland still believed at this stage that Vietnam was no place for the operation of tanks and as a result the M48A3's were withdrawn from the Cav troops and held in reserve at Phu Loi. In effect, this left only the squadron's Air Cav Troop under the operational control of the squadron headquarters.
AP BAU BANG
The first major engagement involving US Armor was by Troop A, 1st Squadron, 4th Cavalry in the battle of Ap Bau Bang. On 11th November 1965, Troop A 1/4th Cav, Company A 2/2nd Infantry and Battery C 2/33rd Artillery, were attacked in their NDP. The attack took place at dawn and, unfortunately for the VC, the whole NDP had been put on an early 'stand to' in anticipation of a possible attack. The VC launched three assaults against the perimeter but were met by a hail of fire from the armour (including M106 mortars) and artillery resulting in 198 confirmed VC KIA's, whilst US losses were two M113's and three M106's.
By late 1965, General Westmoreland was beginning to see the value of armour (ground cavalry) as a hard-hitting and highly mobile force and subsequently requested the deployment of the famous 11th Armored Cavalry Regiment (deployed September 1966) as well as the 25th Infantry Division, the latter to be deployed with it's integral armored and mechanized units left intact.
Whilst initial concerns regarding the unsuitability of armour in the combat environment of RVN proved to be unfounded, nonetheless, cavalry unit tactics had to be substantially modified. This was particularly true in the area of countering ambushes.
11th ARMORED CAVALRY REGIMENT
11th ACR was initially tasked with securing the roads and provinces around Saigon but were soon mounting operations off-road. Up until this time, the enemy had been decimating convoys almost with impunity. 11th ACR soon began to turn the tide in this area and using their heavy firepower and high mobility they would fight clear of an ambush while protecting the vehicles they were escorting. Within the center of their formation the unarmored vehicles could take refuge.
One tactic developed was the 'herringbone' in which the armored vehicles turned alternatively to the side of their direction of march placing their heaviest armour and armament towards their flanks where it could be employed with devastating effectiveness. The armour generally attempted to break out of the kill zone by the use of maneuver and firepower and then turn around to engage the enemy flank while calling in tactical air and artillery support onto enemy concentrations to their front.
Despite initial reservations about the role of armour in Vietnam, by early 1967 the US Army had deployed the following:
PILE ON & THUNDER ROAD
It was not long before US Armor commanders began to better understand the nature of the war they were fighting and the most suitable and destructive means of deploying their armor assets. From Patton's concept of 'Pile on' where a small US force would be used as a bait which, if the enemy took, would soon be massively reinforced by awaiting reserves, to the use of armor as the 'hammer' in rapid hammer-and-anvil maneuvers wherein airmobile infantry were rapidly deployed to the rear of an enemy force and the armor would be used to herd the enemy into the kill zone from which few escaped. Similarly, mechanized infantry were soon mounting highly mobile search and destroy missions even during the wet season.
Using armor in this fashion enabled the US to attack into the heartland of NVA and VC sanctuaries whether they be in the dense jungles bordering Cambodia and Laos, the flooded paddies of the Mekong Delta or the relatively wide open spaces of the Iron Triangle.
Also, whereas the night had always 'belonged to Charlie', the latitude given to the VC and NVA prior to the arrival of armor was increasingly restricted. The famous night-time 'Thunder Run' where an armored column would, quite literally, thunder along down a road firing all available weaponry into the adjacent terrain with a view to either spoiling NVA/VC activities or to pre-empt ambushes and mine laying became a common occurrence.
ON THE OFFENSIVE
The build-up of armored forces in RVN was such that, by 1967, the US was afforded the opportunity to take far more aggressive actions against the enemy in RVN than was previously thought reasonable. Areas which had long been considered as safe sanctuaries for the the enemy could now be entered, attacked and cleared. Operation Cedar Falls (in the Iron Triangle, mentioned above) was one such operation as was Junction City where armored units were utilized to provide road security, convoy escort, search and clear operations as well as rapid reaction force duties. More traditional cavalry operations were also seen such as the rapid relief of Firebase Gold which, in timely fashion, arrived just in time to prevent it being totally over-run.
Mobility and flexibility were the keys to armored success during the Tet offensive. From positions on the borders of Cambodia and Laos, where armor interdicted the early movement of NVA and VC forces infiltrating into RVN, to the swift relief of Saigon, Pleiku and Kontum, armored units were able to sweep down on unsuspecting enemy formations and wreck havoc.
Key installations at Tan Son Nhut and Long Binh-Bien Hoa, which were primary targets for the offensive, were rapidly reinforced by armored columns such as 3rd Squadron, 4th Cavalry who, upon arrival at Tan Son Nhut were able to drive a wedge between the attacking forces and helped pin over 600 VC between themselves and the artillery defending the base. Between the armor, artillery and gunships, over 300 enemy were KIA. 2nd Battalion, 47th Infantry carried out similar reinforcing operations at the major logistical base of Long Binh - Bien Hoa where they cleared a force of enemy sappers from the huge US ammo depot.
Following Tet, with the VC practically eliminated as a cohesive fighting force, US Armor swiftly regained the initiative. NVA and VC units were badly mauled in III Corps by 1st Brigade, 25th Infantry Division as well as in I Corps where 1st Squadron, 1st Cavalry, 23rd Infantry Division blocked NVA units advancing on Tam Ky City. NVA units involved in this particular operation were wholly inexperienced in combating US armor and as a consequence they suffered grieviously at the hands of the mechanized 1st Brigade, 5th Infantry Division.
US Armor strength peaked in 1968 and in early 1969 the only engagement between US armor and communist armor took place at the special forces camp of Ben Het. This particular camp was strategically placed overlooking the Ho Chi Minh trail and thus presented a prime target for the NVA and VC. Tanks from 1st Battalion, 69th Armor had been stationed at the camp since early in the year. In February they were used in a counter-battery role against the enemy who shelled the camp heavily. On March 3rd 1969, the enemy attacked with PT-76 tanks and APC's. US M48A3's engaged the enemy armored forces using HEAT ammunition and destroyed two PT-76's and an APC. As far as US armor was concerned, this was the first, and last, engagement with NVA/VC armor.
Remaining operations in 1969 were mostly concerned with disrupting enemy logistical bases within RVN in operations such as Montana Raider. These operations helped to clear the bulk of the enemy from within the country and having completed that task, the armored units were switched to border security.
Over the course of '69 and '70 the pace towards Vietnamization increased and the activities of US units were wound down to an increasingly advisory role. As US units began to withdraw from Vietnam, armored units found themselves remaining in RVN in some cases even after their parent Division had redeployed back to the USA. The reason for this was that with their mobility and firepower, armored units could still project considerable combat power despite their relatively low numbers of troops.
In May of 1970 operations were launched into Cambodia and many of the remaining US armored units took part; 2nd Battalion, 34th Armor; 2nd Battalion, 47th Infantry (Mechanized); 11th Armored Cavalry Regiment and 3rd Squadron, 4th Cavalry. These units were able to secure vital objectives, block enemy routes of retreat and seize prodigious quantities of enemy supplies. However, the long lines of logistical supply, based on the coast of RVN, had put a great strain on those armored units taking part and a great many vehicles had to be towed back into RVN at the end of the operation. By 30th June 1970, all US armored units were back in RVN.
LAM SON 719
By the time of Operation Lam Son 719, the ARVN incursion into Laos, US units had been banned by Congress from taking part in any further cross-border operations. Despite this limit on their operational use, US Armored units nonetheless played an active part in the operation by securing ARVN logistical routes and the ingress/egress of ARVN forces to and from the borders of Laos.
US ARMOR DEPARTS RVN
As US withdrawal from RVN continued, Armored forces found themselves accounting for more than 50% of US combat strength in RVN. The last US ground Cavalry unit to conduct operations was Troop F, 17th Cavalry. which departed RVN in April 1971. Some air cavalry units remained until 1973, many of which took an active part in the operations against the 1972 Communist Easter Offensive.
Armor of the Vietnam War; (1) Allied Forces, Michael Green & Peter Sarson, Concord Publications Ltd
Armor in Vietnam; A Pictorial History, Jim Mesko, Squadron/Signal Publications Inc.
Vietnam Order of Battle, Shelby Stanton, US News Books
The US Army in Vietnam, Leroy Thompson, David & Charles Publishers
The Rise & Fall of an American Army Shelby Stanton, Spa Books Ltd.