Chapter IX: 
 
Tam Ky
(March 1968)
 
In early 1968, elements of the 23d Infantry Division (Americal) fought a sharp, decisive battle near the village of Tam Ky in Quang Tin Province. This action demonstrates the use of armored cavalry in the Vietnam War. The cavalry role was expanded, particularly in conjunction with air scouts, and armored vehicle doctrine was modified to suit the Vietnam environment.   

A good example of the armored cavalry in Vietnam is the operation of the 1st Squadron, 1st Cavalry, 23d Infantry Division, at Tam Ky. The squadron included three armored cavalry troops plus an air cavalry troop, Troop C, 7th Squadron, 17th Cavalry. (This unit had just returned from an operation in the Pineapple Forest west of Tam Ky.) At the time, the division was using Lieutenant Colonel Walter C. "Mike" Cousland's cavalry squadron as a separate maneuver battalion under division control in his own area of operations against the 72d Local Force Battalion, the 70th Main Force Battalion, and the V-13 and V-15 Local Force Companies. On the evening of 3 March 1968, the squadron, minus two cavalry platoons, was at its base camp on Hawk Hill. The 1st Platoon of Troop A was on Hill 10, securing a sector of Route 1; the 2d Platoon of Troop A was at Tam Ky, prepared to assist in the defense of the province headquarters. Earlier in the day, Captain Michael B. Prothero had assumed command of Troop C. Little did he realize that in less than twenty-four hours he would be commanding his troop and a rifle company against a North Vietnamese Army regiment.   

Captain George R. Kaczor, the squadron's S-2 (officer in charge of the military intelligence section), was busily studying his intelligence reports. Major Wade E. Medbery, Jr., the S-3 (officer in charge of the operations and training section), had issued Colonel Cousland's orders for the next day. In the tactical operations center, all was quiet with the exception of an occasional periodic situation report. Suddenly the silence of the evening was broken by a loud explosion followed by a heavy bombardment of forty-five rounds of 122-
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mm. rockets and fifty rounds of mortar fire. Apparently the enemy was close by and in considerable strength.   

At first light the air cavalry discovered the rocket-firing positions on Hill 34 to the west of the base camp. The commanding general extended the cavalry's area of operations to the west and attached one company of infantry. The squadron was again to be committed as a maneuver battalion to eliminate the enemy force that had fired on it. Troop C was ordered to move to the west to link up with Company A, 3d Battalion, 21st Infantry. About that time, fifteen North Vietnamese soldiers were sighted in bunkers, and the S-3 requested an immediate air strike. At 0938 hours, Troop C started moving toward the area of contact as the air cavalry discovered more and more enemy positions. Some small arms fire was being received by the aircraft, and one Huey was hit but continued to fly. The forward air controller arrived on station and asked the air cavalry to mark the target area. Fighters completed the first air strike at 1100 hours.  

The linkup of the infantry company and Troop C was completed shortly after noon. Colonel Gousland designated the cavalry troop's leader as the team commander and gave him operational control of the air cavalry in the area of contact. The enemy was defending from well-fortified positions. Throughout the afternoon the cavalry-infantry team tested the enemy's positions, pulling back periodically to let the fighters strike. Finally, the North Vietnamese could take no more. As they began to withdraw, the last air strikes and the artillery took a heavy toll.   At 1920 Troop C and Company A, 3d Battalion, 21st Infantry, moved to a night defensive position on Hill 34-the same hill from which the enemy rockets had been fired a few hours earlier. Hill 34 was triangular in shape, with rice paddies and streams on two of its three sides; it was an excellent defensive position. The field of fire over the rice paddies. was well suited to the long-range, direct fire weapons on the tanks and armored cavalry assault vehicles. This position guarded the Phu Xuan River, a known enemy route, allowed observation of the enemy position, and prevented the enemy from using the same firing data against Hawk Hill as was used the previous night.   

Captain Prothero closed his units into the night location at 2012 hours. It had been a hard day for the cavalrymen and infantrymen, but the task of preparing the night defense was vitally important. The men learned that they were dealing with the 3d Regiment of the 3d North Vietnamese Army Division. The enemy had originally intended to attack Hawk Hill, but Captain Prothero's force had thwarted his efforts. While Colonel Cousland and his staff planned the next day's operation, the troops started working on their defenses. The general
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PICTURE: Armored Cavalry Assault Vehicles With RPG Screens on Front
ARMORED CAVALRY ASSAULT VEHICLES WITH RPG SCREENS ON FRONT       

trace of the position resembled the old wagon train coils of the Indian wars on the American plains.

The armored vehicles themselves provided protection against the enemy's small arms and automatic weapons, but the men added a new device to protect the vehicles against the armor-piercing B40 rocket-propelled grenade (RPG). It was called the RPG screen. Nothing more than a section of "cyclone" fence, it caused a shaped charge warhead to detonate before it hit the vehicle. Each crew set up a section of fence in front of its position, and the command element in the center established a second screen around its vehicles. This simple expedient saved many vehicles and bunker positions.   

Fighting positions were built between each cavalry vehicle, and some of the M60 machine guns on the armored cavalry assault vehicles were dismounted and positioned to provide grazing fire. Each vehicle carried three or four rolls of concertina barbed wire. The wire was strung as an outer barrier. Finally, four or five claymore mines were set up in front of each armored vehicle. Listening posts were sent out, and Team C waited for the enemy.   

Except for a few rounds which landed about 100 meters outside the perimeter at 2255 hours, the 3d North Vietnamese Army Regiment let the team alone that night. During this lull, Colonel Cousland analyzed his situation and prepared for the next day. He decided to send Troop C and Company A back into the area of contact in the morning and to attack the suspected enemy positions from the rear.
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 PICTURE: Armored Personnel Carriers Clear the Way as Infantry Follows using vehicles for cover
ARMORED PERSONNEL CARRIERS CLEAR THE WAY AS INFANTRY FOLLOWS Using vehicles for cover.

Two previously planned air strikes were made on the area shortly after first light, followed by an artillery preparation. After an aerial resupply of ammunition, the cavalry-infantry team moved out with air cavalry elements on either flank. At 1305 hours the team received small arms and automatic weapons fire at a range of fifty meters. This attack soon developed into a heavy fight which lasted until 1830 hours, when the unit withdrew to its night defensive positions.   

On the third day Colonel Cousland committed Troop B; Troop C, Company A of the 3d Battalion, 21st Infantry; and the air cavalry troop. The battle lasted for several more days and resulted in 436 North Vietnamese soldiers killed and many weapons captured. The 3d North Vietnamese Army Regiment ceased to exist as an effective fighting force.   

 
Much of the battle of Tam Ky was fought by the armored vehicles of the cavalry squadron. The M48 had been the standard medium tank since 1956, but its sister vehicle in the battle, the armored cavalry
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assault vehicle, was modified specifically for the cavalry squadrons in Vietnam. The old machine gun "jeep" had lacked cross-country mobility and armor protection for the crew. Although the M114 had been used for a while as the scout vehicle, it was replaced with the much more reliable armored cavalry assault vehicle (ACAV).

  The ACAV was actually an M113 personnel carrier modified by the addition of an armament subsystem. This "A" kit consisted of hatch armor, a shield for the commander's .50-caliber machine gun, two elbow pintle mounts with gun shields for mounting M60 machine guns on both sides of the M113, and a removable pintle mount on the rear as an alternate mount for one of the M60's. The armored cavalry assault vehicle originated with the 11th Armored Cavalry, which equipped its M1 13's with the armament subsystems before arriving in Vietnam. The idea soon spread through all units in Vietnam. A "B" kit armament subsystem was also developed. It consisted of hatch armor and a shield for the commander's .50-caliber machine gun. This kit was used on the cavalry mortar carriers.

One of the major innovations in the employment oŁ armor in Vietnam was the use of the M113 as a fighting vehicle. In addition to being used to transport troops to a battle area, it was employed like a light tank, using the fire from mounted weapons to destroy the enemy in close combat. The infantrymen rode on or in the carrier until contact with the enemy was made, then they dismounted. Carriers led the assaults, clearing paths through the underbrush as they went. In many cases, particularly in dense foliage and mine-infested terrain, the infantry troops did better to remain mounted and assault the objective as the carriers detonated antipersonnel mines and booby traps. Most of the personnel carriers, which were used as assault vehicles, were modified as armored cavalry assault vehicles. This technique was discussed by Major General John J. Tolson, III, Commanding General, 1st Cavalry Division (Airmobile). 

[The APC's] didn't have the 90mm guns as did the tanks, but they had the APC's armor protection for the personnel. Their 50 cals. were still a great help in going into the fortified positions. Actually, on occasions, we used the APC platoons very similar to the tank platoons.   The tanks which fought in the battle of Tam Ky in March 1968 were M48A2's. Although their firepower, armor, and maneuverability endeared them to the tanker, their weight and bulk was often more than was needed. The M551 "General Sheridan" armored reconnaissance airborne assault vehicle had been under development as "a lightweight armored vehicle to support ground reconnaissance." In mid-1969 it began to replace some of the tanks in the armored cavalry squadrons.
The relatively large 152-mm. gun and launcher fired combustible-case conventional ammunition. It could also fire the Shillelagh missile
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  but was not used for this purpose in Vietnam. The gun was superior to the 90-mm. tank gun against both bunkers and personnel, and its canister round was excellent to open up bamboo thickets. A disadvantage of the M551 was its limited ability to "bust" through dense jungle. The main battle tank was greatly superior in this respect. 
 
In phasing in the General Sheridans, the 11th Armored Cavalry was issued three Sheridans for two of the ACAV's in the reconnaissance platoon. Thus, the cavalry troop lost none of its jungle-busting ability and greatly increased its firepower. In the division's cavalry squadrons, however, tanks had been assigned to each cavalry platoon instead of to a separate tank troop. The Sheridan was substituted on a one-for-one basis for M48 tanks, resulting in a loss of jungle-busting ability.   
 
An excellent example of the Sheridan's fighting capabilities occurred on 11 March 1969, almost a year after the battle of Tam Ky, when Captain John W. Wells, III, moved Troop A, 3d Squadron, 4th Cavalry, into a night defensive position. He was located at a road junction west of the Ben Cui Rubber Plantation along a known enemy infiltration route. Judging from the results, the enemy did not realize the unit was there. All of the Sheridans in the perimeter were equipped with night observation devices. One of the crews detected a group of enemy troops in an open field, moving directly toward it. Captain Wells instructed the crew to hold its fire and load its canisters. He then moved to the Sheridan to observe the enemy movement personally. As the enemy came closer, the large number of radios indicated that this unit was the command group of a North Vietnamese battalion.   
 
When Captain Wells gave the order to fire, the first round eliminated the whole command group. Having lost its leadership, the enemy soldiers panicked and milled around in the area. In a few minutes the enemy lost forty-two men killed in action and one prisoner of war as compared to two U.S. soldiers wounded. This encounter demonstrated that the Sheridan was a significant combat weapon even during hours of darkness.  
Frequently, tanks from the division tank battalion were attached to the cavalry squadron when additional jungle-busting power was needed. Another solution to the problem was to attach one or two combat engineer vehicles (CEV), M728, to the squadron for certain operations. The need for a combat engineer vehicle first arose during World War II in the hedgerows of Normandy, when bulldozer blades were fitted to tanks, but it was not until Vietnam that such a vehicle arrived on the battlefield. The M728 had been designed to support armor and mechanized units through fire-swept areas and to accomplish a broad range of combat engineering tasks. It was assigned to the division engineer battalions. The combat engineer vehicle is a
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  PICTURE: "General Sheridan" Armored Reconnaissance Airborne Assault Vehicle
"GENERAL SHERIDAN" ARMORED RECONNAISSANCE AIRBORNE ASSAULT VEHICLE 
 
modified M60 tank with a bulldozer blade, a turret-mounted A-frame and winch, and a 165-mm. demolition gun. With its armor protection, this vehicle could move forward under enemy fire to destroy obstacles and fortifications with its demolition gun, clear obstacles with its bulldozer blade, and use the A-frame to lift equipment or place and recover bridges.
In the 23d Infantry Division (Americal), the combat engineer vehicle repeatedly proved to be a valuable asset to engineer and infantry operations. The vehicle was used in fire support, base security, counterambush fire, direct assault of fortified positions, and limited reconnaissance by fire. It even spearheaded an infantry-cavalry charge in the village of  Tap An Bac on 19 June 1969, when division elements came to the defense of two bulldozers and a work party from the 26th Engineer Battalion. The day-long fight was won in the final assault. The M48 tank saw combat for the first time in Vietnam. For the most part, tanks were part of a tank-infantry or cavalry team and conventional tactics were used. Commanders did, however, seek better ways to use their limited armor assets.
In December 1966, the 2d Battalion, 34th Armor, was assigned to secure the route from Tay Ninh to Tri Tam, where small groups of Viet Cong had been successfully mining the road. The battalion commander chose to use the "thunder run" technique to offset this enemy action. During the hours of darkness, a tank company or platoon "ran
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PICTURE: Combat Engine Vehicle
COMBAT  ENGINEER VEHICLE
 
the road" two or three times at irregular intervals. It fired canisters and .50-caliber and 7.62-mm. machine guns at likely enemy locations on both sides of the road. After three nights, mining incidents stopped, and the first Chieu Hoi rapier surrendered. He attributed his action to the thunder runs. This technique was used by most of the tank units in Vietnam.   
 
Lieutenant General William R. Peers, Commanding General, I Field Force, Vietnam, made the following comment about tanks.   
 
In the southern coastal provinces .. the monsoon rains are sufficiently light that normally tanks can operate the year round. Here they proved most productive. For example, the provisional U.S. tank platoon in the Phan Thiet area has added more stability to the area than any other single element. Having been successful in blasting the enemy out of their positions on numerous occasions, they have given a high degree of confidence to the ARVN, the RF/PF, and the local population. On the other hand, they are greatly feared by the enemy to the extent that he has tried on numerous occasions, but without success, to destroy or otherwise eliminate them.  
The shock effect of even a single tank in guerrilla warfare was apparent in Vietnam. Lieutenant Colonel Ronald J. Fairfield, Commanding Officer, 1st Battalion, 69th Armor, stated, "The NVA/VC have shown a reluctance to engage tanks where they can be avoided."' A
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  year later, Lieutenant Colonel Paul S. Williams, Jr., while commanding the same battalion, said: "Captured documents and interrogation reports disclose that the enemy is afraid of tanks. We feel what he really fears is the cannister round and its effect. This [feeling] has been justified, to a degree, by the absence of contact when tank and infantry units move together." Obviously, the enemy did fight armored and cavalry units, but usually he either was put in a position where he had to fight or felt that he possessed sufficient strength to defeat the American force. Colonel Donn A. Starry, one of the commanders of the 11th Armored Cavalry, stated, "A cavalry troop well handled was generally capable of fighting anything the NVA could field, at least until additional cavalry and firepower could be mustered."
An example of the cavalry's shock action occurred when the U.S. 1st Infantry Division staged the battle of Minh Thanh road. The division leaked word that it planned to move engineer equipment and supply vehicles between Minh Thanh and An Loc on 9 July 1966. Actually, two armored cavalry troops and one infantry company were sent along the route, and other combat and combat support forces were positioned to assist. When the 272d North Vietnamese Army Regiment spotted the cavalry force from its ambush positions, it attacked. By the time the smoke cleared the enemy regiment had lost 239 dead on the battlefield, 89 captured, and an estimated 304 killed but not visible in the area. The regiment was probably reduced to less than 50 percent of its strength.
Some of the findings of the official "Evaluation of Mechanized and Armor Combat Operations in Vietnam (MACOV)" summarize the effectiveness of armored cavalry units.   
 
Armored cavalry units were employed in roles previously assigned to tank and infantry maneuver battalions to addition to the traditional reconnaissance, security, and economy of force roles. This change has evolved due to the nature of the enemy in Vietnam, the concept of area war and the balanced combined arms structure of the armored cavalry squadron. There are definitive battlefields in the traditional sense, the enemy has a propensity for avoiding contact by moving in small groups-massing only for short term offensive actions. 
 
Armored cavalry squadrons have proven effective not only as a force to find and fix the enemy, but also as an aggressive offensive force. The balanced combined arms of structure and inherent capability for quick response and extended independent action have made it possible to employ the armored cavalry squadron as a well-balanced maneuver battalion.   
The most important materiel innovations associated with mechanized warfare in Vietnam were the combat 
 
engineer vehicles, the M551 General Sheridans, and the modifications of the M113 personnel carrier. These vehicles were integrated with new techniques, such as airmobile tactics, secure communications, and night vision equipment, and proved enormously effective. The rocket-propelled gren-
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ade screen was one of the most widely used innovations of the war. Cyclone fence could be found at virtually every U.S. installation in Vietnam. The concept of detonating enemy rocket-propelled grenades before they hit the target was sound, and the adaptation of existing materiel for this use was ingenious.  
 
The use of the M113 in a tank-like role will interest the military theorists for years. The M113 brought to the Vietnam battlefield the shock, firepower, and mobility that are characteristic of tank warfare. The terrain was less than ideal for tanks; the enemy's forces included no significant armor formations. Given these conditions, it is not surprising that the M113 was often used as a tank.   
 
The development of jungle-busting techniques and thunder runs was the logical outgrowth of mechanized forces in the Vietnam environment. Every combat commander in Vietnam faced the problems of jungle warfare and enemy mines. Jungle-busting was the only way to exploit mechanized mobility in the forests, and the firepower and shock action of an M113 or a General Sheridan was invaluable to a force in an occupied enemy base camp.   
 
U.S. armor and mechanized formations made a significant contribution to the allied effort in Vietnam. The armor soldier with modern equipment, training, and leadership proved his effectiveness and gave the Viet Cong and North Vietnamese Army ample reason to avoid tanks where they could.
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