Chapter IV: 
Combined Arms Operations
Armored units fighting in Vietnam by early 1967 included one armored cavalry regiment, six mechanized infantry battalions, four armored cavalry squadrons, two tank battalions, an air cavalry squadron, and five separate ground cavalry troops. By this time it was apparent that armored units of all types were proving far more useful in combat than had previously been thought possible. General Johnson, Army Chief of Staff, after discussions of the use of armor with General Westmoreland in the summer of 1966, directed the Army staff to determine whether a pattern of armored operations involving both tanks and armored personnel carriers had begun to emerge in Vietnam. The resulting staff study recommended an analysis by the U.S. Army Combat Developments Command for the purpose of suggesting modifications in unit organization, equipment, training, and deployment.
The MACOV Study
In August 1966 General Johnson approved plans for a study titled Mechanized and Armor Combat Operations in Vietnam (MACOV) under the direction of Major General Arthur L. West, Jr. Between January and March 1967 a group of over 100 American Army officers and civilian analysts examined the combat record of armored and mechanized forces in Vietnam, gathering and studying information gleaned from the battlefield. The group evaluated over 18,000 questionnaires, 2,000 reports, and 83 accounts of combat in which battalions and larger units had participated. Its report did not subscribe to the opinion that Vietnamese jungles and swamps would swallow up armored vehicles, but concluded that habitual use of armored vehicles against insurgents in jungles and swamps necessitated some changes in armor tactics. The group found that extensive use had been made of the armored personnel carrier M113, modified with weapons and gunshields to become a tanklike fighting vehicle that was known as the ACAV-armored cavalry assault vehicle. The study group also found that more often than not U.S. mechanized infantry fought mounted, employing armored personnel carriers as assault vehicles to close with and destroy the enemy, and that mounted troops generally suffered fewer and less serious casualties

than foot soldiers. Contrary to established doctrine, armored units in Vietnam were being used to maintain pressure against the enemy in conjunction with envelopment by airmobile infantry. Moreover, tanks and APC's frequently preceded rather than followed dismounted infantry through the jungle, where they broke trail, destroyed antipersonnel mines, and disrupted enemy defenses. These findings revealed that some departures from armor doctrine had been taking place.
The study group noted several of the special advantages armor possessed in area warfare, described enemy tactics against armor, and listed types of armor missions. The group concluded that while tank and mechanized infantry units were playing a significant role in Vietnam, cavalry units, both ground and air, were essential elements to the important business of finding, pursuing, and destroying the enemy. Among its important recommended changes for armored and mechanized units was that organization be standardized for future armored forces being sent to Vietnam. This recommendation followed the discovery that, because of extensive and undisciplined modification of tables of organization and equipment, no two armored units in Vietnam were organized alike. Believing it impossible for the Department of the Army to support such a diverse force structure, the study group recommended that the Army strictly enforce conformity with modified standard tables of organization and equipment of units going to Vietnam.
Major findings of the study were described in a training manual, a training film, and an air cavalry text; all were given worldwide Army distribution. The air cavalry training text in particular was used for several years by air cavalry units and provided a much needed reference work to explain the air cavalry mission to ground commanders unfamiliar with the concept. It was also useful in training troops scheduled to deploy with air cavalry units.
The training manual's coverage was very broad, and when used correctly the manual was a "how to" book for armored units in Vietnam. Considering that most of the information bad never been published in one book before, the manual was a landmark. General Westmoreland wrote the foreward and later commented that the
study had prompted him to ask for more armored and mechanized units in troop requests. The text discussed impassable terrain and maps showed the areas that could be traversed in the wet and dry seasons. (See Maps 2 and 3.) In addition, it described the enemy and the frustrating nature of area warfare. Various battle formations and procedures such as herringbone, thunder run, and roadrunner were described in detail. The manual also discussed the

cloverleaf, a maneuver particularly suited to armored units, mounted or dismounted, when they were making a rapid search of a large area.
The impact of the study was something less than many hoped for. The findings were not surprising to amored troops who had served in Vietnam but were regarded with a jaundiced eye by others who had not served there. Some data collectors believed that they were called upon to justify the existence of armor units already in Vietnam or scheduled to go there, but most members of the study group were able to put their task into perspective, and none expressed the justification for the study so well as one who said, "Although I did not doubt the value of armor in Vietnam, I was, myself, unable to recommend how much, of what type, and where it could be deployed. It would take a study like MACOV to provide a basis for these recommendations."
The bulk and security classification of the report prevented its widespread dissemination. In seven thick volumes, the official study was classified secret and was supported by six classified data supplements nearly as long as the report itself. Although its volume and classification were necessary, potential readers were overwhelmed. Only 300 copies were printed, and few remain in existence today. The publication of the unclassified training manual and film was an effort by the study group to gain wider circulation for the information.
At the U.S. Army Armor School and the Combat Developments Command Armor Agency at Fort Knox, changes in troop and equipment tables were enthusiastically endorsed, but doctrinal changes were rejected. While the report was clearly intended only to supplement worldwide armor doctrine, both the agency and the school argued that the new concepts were not applicable to armor combat in other parts of the world. Apparently those engaged in formulating doctrine were less concerned with the study group's conclusions, which were based on several years of combat experience in Vietnam, than they were with hypothetical situations in other parts of the world.
The training establishment under the Continental Army Command (CONARC) was unwilling to accept the study group's observations on the unprecedented role of M113's as assault vehicles in Vietnam. The command noted that the term "tanklike" was misleading and that adopting as doctrine the employment of mounted infantry in a cavalry role was neither feasible nor desirable. Justification for its position seemed to be couched in contradictory terms. While the command agreed that more Vietnam-

PICTURE - HERRINGBONE FORMATION ASSUMED BY 31) SQUADRON, 11TH ARMORED CAVALRY, DURING OPERATION CEDAR FALLS, This formation gave vehicles best all-round firepower when they were ambushed in a restricted area.
HERRINGBONE FORMATION ASSUMED BY 3d SQUADRON, 11TH ARMORED CAVALRY, DURING OPERATION CEDAR FALLS, This formation gave vehicles best all-round firepower when they were ambushed in a restricted area.
oriented training and doctrine were needed by deploying units, it refused to heed those findings of the study that were most attuned to the actual combat situation in Vietnam. The Continental Army Command decided to leave the matter to the interpretation of local commanders, although these were the same commanders who had told the study group that a revision of doctrine was needed to reflect actual combat experience in Vietnam.
The command also rejected the report's recommendation that the psychological effect of armored and mechanized units upon the enemy be exploited, stating that any further study of this matter would probably be superfluous. The implication was that the psychological advantage was not that great in the first place. "The Vietnamese people," stated the Continental Army Command, "know too well of the French Armored Mechanized Units' defeat at the hands of the Viet Minh and the destruction that can be inflicted on a tracked vehicle by one Viet Cong with a small amount

Diagram 6. Cloverleaf search technique used by armored cavalry troops.
Diagram 6. Cloverleaf search technique used by armored cavalry troops.

of properly placed demolition material." To some elements within the command, the shock effect of armor, whether concrete or psychological, no longer existed, at least not in the case of the Viet Cong or the North Vietnamese Army.
The Army's equipment developer, the Army Material Command, and the doctrine agency, the Combat Developments Command, both commented on the report. The Army Material Command endorsed the majority of the study group's equipment recommendations but out of necessity qualified the approval with cost and time factors; it frequently noted feasibility but implied impracticality. The Combat Developments Command concluded that, with few exceptions, the recommendations should be carried out for Vietnam, and that certain of them were applicable to the Army worldwide.
The Combat Developments Command forwarded to the Department of the Army a strong endorsement of the study group's suggestion that increased emphasis be placed on the use of armored forces in warfare such as that in Vietnam. While the Army staff approved many specific recommendations, it did not agree that increased use of armored units in Vietnam was either necessary or desirable. In spite of the study group's observations on the usefulness of the M113 as an armored assault vehicle, the Army staff considered the results of such employment could only lead to a pyrrhic victory at best: "To modify and employ this means of transportation as an armored assault vehicle," it noted, "against an enemy who is daily improving the lethality and effectiveness of his armament not only decreases the capabilities for which the vehicle was originally designed, but can result in unnecessary friendly casualties." This position was totally inconsistent with the real world situation in 1967 in which U.S. and South Vietnamese armored forces were habitually and effectively employing their APC's and ACAV's as assault vehicles with great, success.
One other circumstance worked against widespread acceptance of the recommendations: As the study group was preparing to leave for Vietnam in November 1966, Defense Secretary McNamara imposed an absolute troop ceiling on U.S. forces in Vietnam. This arbitrary ceiling was well below the total number already in the proposed troop program of the U.S. Military Assistance Command, Vietnam, and the United States Army, Vietnam. In other words, if more armored forces were wanted, other units had to be given up in order to get them. The situation was complicated by the fact that recommendations of an earlier study, Army Combat Operations in Vietnam, completed in 1966, had not yet been acted

upon. The earlier recommendations dealt with infantry problems in Vietnam in the same detail as the armor study dealt with armor problems; they also required trade-offs, most of which had not yet been decided upon.
The armor study group applied itself to this problem in a straightforward way by incorporating the infantry study recommendations and summing up the cumulative effect of both studies. The group then selected some 4,000 troop spaces in the proposed force for the US. Military Assistance Command, Vietnam, that could be traded to carry out the combined recommendations of both studies. Since the spaces came largely from combat support troops, the logistics and administrative community vehemently denounced the trade-off, thereby heightening the opposition to the study group's recommendations.
The armor study raised again all the historic arguments for and against the use of armored forces in Vietnam. It provided a documented basis for discussion and, in fact, influenced the training and employment of many armored units. The Department of the Army subsequently approved organizational and equipment changes incorporating some of the recommendations. The armored cavalry assault vehicle, for example, is in the Army today, and fighting mounted from armored vehicles is an accepted practice. Vietnam related training at the Armor School was increased from two to twenty hours in mid-1967, although academic department heads expressed concern that the Army would overemphasize Vietnam at the expense of conventional armor employment. This attitude was in striking contrast to that of junior officers and students who knew they were destined for duty in Vietnam.
Armored units scheduled for Vietnam used the armor study group's training manual as a guide, but copies were difficult to obtain; many armor officers never saw it. Only a few years later, units and service schools were hard put to find the copies they had received.1 Perhaps the most effective dissemination of the study findings came through the efforts of the group members, some of whom wrote service school lesson plans, contributed articles to periodicals, and made changes in units in which they served. All in all, the armor study accelerated changes in the theory of using armored forces that would be tested and validated by the battles of the Tet offensive of 1968.

Cedar Falls-Junction City
Early combat operations in 1967 that were observed, recorded, j and analyzed by General West's study group reflected a definite change in strategy for American and other free world forces in Vietnam. Until late 1966 General Westmoreland had employed "fire brigade tactics," reacting to enemy initiatives with his limited I troop resources. By 1967 the buildup of U. S. forces permitted him some flexibility, and increases in tactical mobility improved the I effectiveness of the reaction forces. Thus, in 1967 the mission of American and other free world units changed to one of offensive action against the main force enemy units. South Vietnamese forces were to be employed primarily in pacification. The initiative was passing to the free world forces.
In the III Corps Tactical Zone the first deliberately planned multidivision operation, CEDAR FALLS, was begun by II Field Force, Vietnam. The target was an extensive enemy base and logistical center that because of its geographical shape and strong defense was known as the Iron Triangle. (Map 8) This heavily jungled area, twenty-five kilometers north of Saigon, was an important center for the launching of enemy guerrilla and terrorist operations; it was frequently referred to as "a dagger pointed at Saigon." The plan was to seal the area, split it in half, thoroughly search it, and destroy all base camps and enemy forces.
The Iron Triangle was sealed by U.S. armored and airmobile units. The 2d Battalion, 22d Infantry (Mechanized) ; 1st Battalion, 5th Infantry (Mechanized) ; 2d Battalion, 34th Armor, and Troop B, 3d Squadron, 4th Cavalry, established blocking positions west of the Saigon River; the 1st Squadron, 4th Cavalry, E Troop, 17th Cavalry, and Company D, 16th Armor, were employed east of the Thi Tinh River. Having moved to an assembly area the day before, the 11th Armored Cavalry, less its 1st Squadron, attacked west from Ben Cat on 9 January to divide the area in two. Throughout the operation, units combed the Iron Triangle, uncovering base camps, food, equipment, and ammunition. Fighting was light and generally limited to scattered encounters with platoon-size or smaller groups. The value of CEDAR FALLS does not lie in the number of enemy casualties it produced but in the 500,000 pages of enemy documents it captured. These exposed the command structure and battle plans of the entire Viet Cong and North Vietnamese Army hierarchy. General Seaman described the operation as the largest intelligence breakthrough in the war.
Tracked vehicles, which had little difficulty in traversing the terrain, were assisted in the search by bulldozers. A task force of


fifty-four bulldozers with four Rome plows and some tanks with dozer blades cleared more than nine square miles of jungle, and frequently led armored columns. In an interesting innovation, the 2d Battalion, 34th Armor, used tank-mounted searchlights to detect Viet Cong night movements along the Saigon River. Several successful night ambushes were conducted by directing tank fire against the enemy river traffic.
The wisdom of the 1966 decision to increase the number of mechanized infantry battalions from two to six was attested to by Brigadier General Richard T. Knowles, Commanding General, 196th Light Infantry Brigade, in a statement concerning the role of mechanized infantry in CEDAR FALLS.
Mechanized infantry has proven to be highly successful in search and destroy operations. With their capability for rapid reaction and firepower, a mechanical battalion can effectively control twice as much terrain as an infantry battalion. Rapid penetrations into VC areas to secure Us for airmobile units provide an added security measure for aircraft as well as personnel when introducing units into the combat zone. The constant movement of mechanized units back and forth through an area keeps the VC moving and creates targets for friendly ambushes, artillery and air.

The 11th Armored Cavalry Regiment's success in CEDAR FALLS clearly confirmed the soundness of the unit's organization. The regimental commander, Colonel William W. Cobb, reported that the first rapid maneuver into the area and its accomplishment of search and destroy, screening, blocking, and security missions demonstrated the flexibility of his unit. He further stated:
The search and destroy portion of Operation CEDAR FALLS was the final combat test of the modified TOE designed to tailor the regiment's organization to the requirements of the counterinsurgency operations in Vietnam. The search and destroy operations, plus the allied saturation and sniper patrols, and tunnel search operations proved the validity of the MTOE. There proved to be sufficient personnel in the basic maneuver element-the Armored Cavalry Platoon-to allow for required dismounted tunnel and patrolling operations while maintaining sufficient crew members on the ACAV's to maintain the platoon's mounted combat capabilities.
When Operation CEDAR FALLS ended on 25 January 1967, armored forces of II Field Force, Vietnam, were committed to Operation JUNCTION CITY, the largest operation of the war to that date. JUNCTION CITY was designed to disrupt the Viet Cong Central Office for South Vietnam (COSVN), destroy Viet Cong and North Vietnamese forces, and clear the War Zone C base areas in northern Tay Ninh Province, eighty-five kilometers northwest of Saigon. During the three-phase operation, armored units served in road security and search and clear operations and acted as convoy escorts and reaction forces.
Phase I, 22 February-17 March, consisted of establishing a horseshoe blocking position in northwestern War Zone C, then attacking into the open end of the horseshoe toward the U end of the position. From Fire Support Base I at 0600 on 22 February, a 1st Squadron, 4th Cavalry, task force began a twenty-kilometer move north on Provincial Route 4; its mission was to reinforce quickly the airborne and airmobile assault elements at the north end of the horseshoe. To send the cavalry along an uncleared route was a calculated risk, prompted by the hope that the enemy would not employ mines on one of his few partially paved supply routes. The gamble worked. The 1st Squadron raced unimpeded to reinforcing positions south of Katum, and the landings went without incident. As the cavalry moved north, the 2d Battalion, 2d Infantry (Mechanized), followed with artillery and engineering units to establish Fire Support Bases II and III.
At dawn on 23 February, the 2d Brigade, 25th Infantry Division, and the 11th Armored Cavalry Regiment began sweeping

north between the sides of the horseshoe. There was scattered fighting as the armored units found base camps, hospitals, bunker systems, and small groups of Viet Cong. Mines and booby traps slowed the attack, and in the center of the horseshoe dense jungle made movement difficult. After reaching the northern limit of advance, the 11th Armored Cavalry Regiment pivoted and swept west with the other forces. Sporadic fighting continued.
For armored units, JUNCTION CITY was a task force operation. Combined arms operations at battalion and squadron level were normal, and mobility was stressed. Armored task forces with attached elements of infantry, artillery, tank, and cavalry roamed through the operational area. Infantry rode on the tracked vehicles and went into action as tank-infantry teams.
Although enemy resistance gradually stiffened throughout the area, the armored task forces finally drew out the elusive Viet Cong on the periphery of the operation. The mobile blocking forces were interfering with Viet Cong supply operations, and the enemy fought back. The resistance was particularly evident along Routes 4 and 13 as the enemy shifted eastward to avoid the JUNCTION CITY attacks. In this area three armored battles took place, each illustrating a different type of combined arms action. The first, at Prek Klok II, stressed firepower; the second, at Bau Bang, demonstrated mobility and staying power; and the third, at Suoi Tre, emphasized mobility and shock action.
While mines were not encountered in the first thrust north on Provincial Route 4, as operations progressed the enemy began to mine the road, hoping to cut the American force's primary resupply route. From random sniping and mining the enemy went to mortar attacks and night probes of fire bases. On the evening of 10 March, Fire Support Base II at Prek Klok II was defended by Lieutenant Colonel Edward J. Collins's 2d Battalion, 2d Infantry (Mechanized) , which was minus its Company B, some engineer troops, and two batteries of 105-mm, artillery. The base straddled an airfield that the engineers were constructing. Tracked vehicles were placed around the perimeter at 50-meter intervals, and artillerymen, engineers, and infantrymen manned foxholes between the APC's. About 2030 a listening post sighted three Viet Cong and immediately pulled back into the perimeter; the base went to 75 percent alert status. An unearthly silence fell. Some thirty minutes later it was broken by the dull thump of enemy mortars firing. In a matter of seconds the entire area erupted with explosions as the enemy poured over 200 rounds of mortar and recoilless rifle fire into the base. When the barrage ended, Colonel Collins ordered the de-

fenders to conduct a reconnaissance by fire of the area 200 to 600 meters beyond the perimeter.2
When the U.S. machine guns fell silent at 2220, the enemy launched a two-battalion ground attack from the east. The first wave of the assault came within hand grenade range, and the perimeter was enveloped in fire as the defenders answered with vehicle-mounted and ground machine guns, small arms, and artillery fire. Intense Viet Cong antitank fire, rocket propelled grenades and recoilless rifles, was directed against the APC's. Although the vehicles were positioned behind a low berm, three were struck by rocket grenades and one received a direct hit from a mortar round.
To support the main attack, smaller enemy forays were launched from the northeast and southeast. Trip flares and listening posts had been set out about fifty meters in those areas. According to Specialist 4 Thomas Lark, when the listening posts were brought in after the mortar attack, "We opened up on the VC when they hit our trip flares and after that we never had any trouble with the VC getting close to our perimeter." A secondary attack was also launched from the southwest, but here the enemy had to cross 500 meters of open ground. Amid explosions of recoilless rifle rounds, the defenders held their positions, pouring machine gun and small arms fire into the attackers. This secondary attack never gained momentum, although heavy enemy fire continued from the wooded area beyond the clearing. Supported by air strikes, artillery, and machine gun fire from "Spooky" (a C-47 aircraft with multi-barrel machine guns) , the defenders repelled the brunt of the attack by 2300.
The battle of Prek Klok II was one-sided, for the enemy lost almost 200 men while the defenders lost three. The enemy had hoped to achieve a quick victory to bolster his sagging fortunes. Instead, a combined arms team of artillerymen, mechanized infantrymen and aircraft, using selective firepower and properly prepared defensive positions, had dealt him a severe defeat.
As JUNCTION CITY continued into Phase II, the enemy lost enormous amounts of supplies and was denied use of his vital communications centers. In an attempt to ease the pressure, the Viet Cong launched a desperate attack on 19 and 20 March against a fire base protected by the cavalry. The base, sixty kilometers north of Saigon near Ap Bau Bang on QL-13, was in flat country


with wooded areas to the north and west and a rubber plantation to the south. (Map 9) It was protected by Troop A, 3d Squadron, 5th Cavalry Regiment, and contained Battery B, 7th Battalion, 9th Artillery (105-mm.) One platoon from the troop occupied Combat Outpost 3, approximately 2,800 meters north. Troop B of the 3d Squadron was located to the north, and Troop C and the headquarters troop were protecting the squadron command post to the south.
At 2300 the northeast section of the fire support base was raked by fire from an enemy machine gun, but the gun was quickly silenced by return fire from tanks and armored cavalry assault vehicles. Shortly after midnight the base came under heavy fire from rocket grenades, mortars, and recoilless rifles, followed by a massed ground assault. Main attacks from the southwest and southeast were supported by a diversionary attack from the northeast. Troop A defenders at first held their own but requested that a ready reserve force be designated for use if needed. The 1st Platoon of Troop B, to the north, and the 3rd Platoon of Troop C, in the south, were alerted to assist.
The battle intensified as enemy troops reached the vehicles on the southwest portion of the perimeter, but with the help of more than 2,500 rounds of sustained artillery fire from all calibers of weapons the cavalry held. At times enemy soldiers were blasted off ACAV's by 90-mm. canister fire from nearby tanks. When the tanks ran out of canister, they fired high explosive rounds set on delayed fuses into the ground in front of the enemy. The result was a ricochet round that exploded overhead and showered fragments over the enemy units - a very effective weapon. Several defending vehicles were hit and destroyed by rocket grenade fire, and the gaps created in the line finally forced the troop to fall back to tighten its perimeter.
At 0115 the squadron commander, Lieutenant Colonel Sidney S. Haszard, gave Troop A permission to move its 2d Platoon from Combat Outpost 3 to the fire base, and ordered Troops B and C into action. The 2d Platoon had to attack the enemy in order to get through to the defenders. When the 3d Platoon of Troop C arrived, the Troop A commander directed that it sweep south of the perimeter along the tree line. Continually firing its weapons, the platoon swept the southwest side of the fire base, then doubled back and entered the defensive line from the southeast. At the same time, while en route to the base at thirty miles an hour, the 1st Platoon of Troop B literally ran over a hastily set ambush. Just as the platoon arrived, the enemy launched another attack. The Troop A com-

mander directed it to sweep the entire perimeter. Circling around the outside of the base with headlights and searchlights flashing and weapons firing, the platoon crushed the attack.
The enemy's next attack, at 0300 from the south, was easily repelled by the five cavalry platoons in the base and air support that eventually totaled eighty-seven sorties through the night. Troop A then conducted a series of counterattacks, clearing an area 800 meters deep around the perimeter and reducing the enemy fire. At 0500 under illumination from flares and searchlights, the enemy could be seen massing for another attack from the south and southeast. Tactical aircraft and artillery were quickly employed and the attack never gained momentum. Although sporadic enemy fire continued, the six-hour battle ended, leaving over 200 enemy dead on the battlefield and three American soldiers killed.
The success of the defense hinged on the mobility of the armored units, the heavy firepower-artillery and air support- and the tactics used. The armored vehicles had not been dug in and were not fenced in with wire. Throughout the attacks, ACAV's and tanks continuously moved backward and forward, often for more than twenty meters, to confuse enemy gunners and meet attacks head on. The movement added to the shock effect of the vehicles, for none of the enemy wanted to be run over. In addition, reinforcing platoons all carried extra ammunition on their vehicles and provided resuppy during the battle.
The last major armored action in JUNCTION CITY occurred only a day after the Ap Bau Bang fight, when the enemy launched an unprecedented daylight attack against Fire Support Base Gold near Suoi Tre. The fire base was occupied by the 3d Battalion, 22d Infantry (-) and the 2d Battalion, 77th Artillery (-) . The 2d Battalion, 12th Infantry, the 2d Battalion, 34th Armor, and the 2d Battalion, 22d Infantry (Mechanized), were conducting search and destroy operations nearby.
The 2d Battalion, 34th Armor, commanded by Lieutenant Colonel Raymond Stailey, moved north on 20 March, led by Company A, 2d Battalion, 22d Infantry, which had been sent to link up with the tanks. By nightfall the two battalions had joined and set up camp within two kilometers of each other. Earlier that afternoon the Scout platoon of the mechanized battalion had cleared a trail about 1,500 meters to the north but had been unable to locate a ford across the Suoi Samat. Lieutenant Colonel Ralph W. Julian, commander of the 2d Battalion, 22d Infantry, decided that the next day his units would move north on the trail, then swing east to search for a ford across the upper reaches of the stream.

On the opposite side of the Suoi Samat, about two kilometers northeast of the tank battalion's position, infantrymen and artillerymen were improving perimeter defenses at Fire Support Base Gold. The next morning at 0630, an ambush patrol from the 3d Battalion, 22d Infantry, engaged a large force of Viet Cong moving toward the base and at the same time the base came under heavy mortar attack. Over 600 rounds pounded the camp as waves of Viet Cong emerged from the jungle, firing recoilless rifles, rocket grenades, automatic weapons, and small arms. The ambush patrol was quickly overrun and was unable to return to the base. As the fighting grew more intense, the armored units to the south were ordered across the Suoi Samat to reinforce the embattled fire base. Colonel Julian immediately moved part of Company C and an attached tank platoon north on the trail cleared earlier by the Scout platoon.
While the remainder of the column closed, conditions worsened at the fire base. Colonel Marshall Garth, the brigade commander, said "If a vehicle throws a track, leave it. Let's get in there and relieve the force." Personnel carriers in the lead straddled each other's paths in order to clear a trail wide enough for tanks, while lead elements using compasses continued their search to the east in an attempt to find the Suoi Samat and a ford.
At Fire Base Gold, counter fire was seeking out the enemy mortars that were pounding the defenders. The enemy concentrated against the east side of the perimeter until, at 0711, Company B reported that its 1st Platoon had been overrun. A reserve force of artillerymen helped to reestablish the perimeter, but fortyfive minutes later the enemy had again broken through the 1st Platoon. Within a few minutes, positions on the northeastern portion of the Company B perimeter were completely overrun by a human wave attack. Company A sent a force with desperately needed ammunition to assist Company B. Then, on the northern perimeter, the Viet.Cong swarmed over a quadruple .50-caliber and attempted to turn it on the defenders, but the weapon was blown apart by the artillery. To make matters worse, Company A reported penetrations in portions of its northern perimeter.
The urgency of the situation was again conveyed to Colonel Julian by Colonel Garth's order that the stream was to be crossed "even if you have to fill it up with your own vehicles and drive across them." Following instructions from a helicopter overhead, the armored column finally crossed the stream and moved toward the fire base. To the northwest the 2d Battalion, 12th Infantry, advancing on foot, had reached the defenders. From the air, Colonel Julian directed Lieutenant Colonel Joe Elliot, Commander of the

2d Battalion, to secure the western sector of the fire base. The mechanized forces were ordered to enter just south of the 2d Battalion, 12th Infantry, and swing around the perimeter, consolidating the remainder.
On the smoke-covered battlefield the reinforced defenders were still in desperate straits. Artillerymen were firing beehive rounds, steel flechettes released at the muzzle of the weapon. When the supply of beehive was exhausted, they switched to high-explosive direct fire at point-blank ranges. The eastern sector of the perimeter had fallen back under heavy pressure to positions around the artillery pieces. The Viet Cong were within five meters of the battalion aid station and within hand grenade range of the command post.
Into this chaos came the tanks and APC's, crashing through the last few trees into the clearing. The noise was overwhelming as the new arrivals opened up with more than 200 machine guns and 90mm. tank guns. The ground shook as tracked vehicles moved around the perimeter throwing up a wall of fire to their outside flank. They cut through the advancing Viet Cong, crushing many of them under the tracks. The Viet Cong, realizing that they could not outrun the encircling vehicles, charged them and attempted t0 climb aboard but were quickly cut down. Even the tank recovery vehicle of Company A, 2d Battalion, 34th Armor, smashed through the trees with its machine gun chattering. Most of the crew, who were all mechanics, were throwing grenades, but one calm mechanic sat serenely atop the vehicle, his movie camera grinding away.
Relief was evident in the faces of the defenders as tracked vehicles quickly tied in with the 2d Battalion, 12th Infantry. "It was," exulted Lieutenant Colonel John A. Bender, the fire base commander, "just like the late show on TV, the U.S. Cavalry came riding to the rescue." Master Sergeant Andrew Hunter recalled, "They haven't made the word to describe what we thought when we saw those tanks and armored personnel carriers. It was de-vine." With victory almost within grasp of the enemy, the tanks and APC's had turned the tide. When the smoke cleared, it was apparent that the enemy had not only been defeated but had lost more than 600 men.
JUNCTION CITY II ended on 15 April as the enemy faded away. Armored units played a major role in JUNCTION CITY and proved that in most areas of War Zone C, a cavalry squadron or mechanized infantry battalion could more effectively control a large area than any other type of unit. Although routes over the difficult terrain had to be carefully selected, tracked units moved through most

of the dense jungled area. Tanks were invaluable in breaking trails through seemingly impenetrable vegetation. The ability of armored forces to move rapidly and to arrive at the critical place with great firepower gave them a significant advantage.
Mechanized Operations in the Mekong Delta
The extensive rice paddies and mangrove swamps of the canal laced delta were very different from the jungled areas of Operation CEDAR FALLS-JUNCTION CITY in III Corps Tactical Zone. But in the delta, with few high elevations, M113's could move as freely as rivers and major canals permitted. The 2d Battalion, 47th Infantry (Mechanized) , and the 5th Battalion, 60th Infantry (Mechanized) , of the U.S. 9th Infantry Division-two armored units employed in this region-conducted successful combined American-Vietnamese operations throughout 1967. Typical missions included reconnaissance in force, route and convoy security, night roadrunner operations, cordon and search of villages, and rapid reinforcement.
Flooded rice paddies slowed, but did not prevent cross-country movement. Small canals up to three meters in width were crossed with balk bridging. In the case of larger canals and rivers, which were major obstacles because their banks were usually steep or composed of loose soil, bulldozers or explosives were used to construct entry and exit routes. Mechanized units quickly discovered that when track shrouds were removed to prevent the buildup of mud between track and hull the M113's swimming ability was impaired. Navy landing craft were therefore required for transportation across major rivers and canals. Route reconnaissance by air was always important but was essential during the monsoon season.
The delta's open, level terrain permitted ground troops to engage with organic weapons at much greater range than that of the point-blank fighting normal in the jungle. One of the hardest battles fought by mechanized infantry in the delta occurred at the village of Ap Bac II on 2 May 1967. Ap Bac II was a base area for the 514th Viet Cong Battalion, and the enemy pattern of movement between base areas had suggested the probability of the battalion's presence near Ap Bac II on 2 May.
The original plan of the 2d Brigade, 9th Infantry Division, was to conduct an airmobile search and destroy operation with two battalions of infantry. On 2 May, however, when no helicopters were available the insertion of a blocking force was deleted from the plan. Movement of two battalions abreast without a blocking force in the rear was regarded by many as "forcing toothpaste

MAP 10
from a tube," and there appeared little likelihood of a significant encounter. Company C, 5th Battalion, 60th Infantry (Mechanized) , manned the left flank under the control of the 3d Battalion, 60th Infantry. (Map 10) First Lieutenant Larry Garner's mechanized company was given the deeper objective because its mobility would permit a quick search of the area. It was hoped that tracked vehicles could make up for lack of a blocking force.
By 0830 the M113's of Company C were advancing north, crossing paddies surrounded by narrow, earthen dikes. Mostly dry, the paddies easily supported tracks, but crossing the many canals and streams proved more difficult. Company C found none of the enemy during its northward sweep; however, to the east, Company A, 3d Battalion, 47th Infantry, encountered stiff resistance as it approached the Suoi Sau. The steep banks of the stream were dotted with thatched huts and lined with dense vegetation. A squad, maneuvering across the stream, was quickly pinned down by heavy automatic weapons fire. Within minutes all who had crossed the

stream had been hit. Two companies of the 3d Battalion, 47th Infantry, moved in on the right of Company A, while Company B. 3d Battalion, 60th Infantry, moved to block the northern escape route. At 1300, with blocking forces in a reversed "C," Company C of the 5th Battalion and Company A of the 3d Battalion of the 60th Infantry were ordered east to fill the open end of the blocking positions. The eleven M113's of Company C had to maneuver through inundated areas that appeared impassable. Crossing two fairly deep streams, the company chose routes that brought it abreast of Company A, 3d Battalion, 60th Infantry, on a 1,000 meter assault line by approximately 1530. Under cover of artillery and air bombardment, the companies crossed more irrigation ditches and by 1700 were poised for the attack. 
On order, artillery fire stopped and the tracked vehicles surged forward, while blocking units supported by fire. The mechanized company moved rapidly across the open rice paddy, its machine guns searching out the enemy bunkers along the wood line. At the woods infantrymen dismounted and attacked the enemy soldiers who had been pinned down by heavy fire. Although stunned by the shock of the assault, the Viet Cong continued to resist, and the infantry was forced to move among the bunkers destroying the enemy with grenades.
Company A, moving on foot to the right of Company C, met heavy resistance and finally stalled about 100 meters from the bunker line. The company commander requested help from Company C, which responded by moving four M113's to aid the dismounted attack. Since darkness had set in, further reinforcement was considered impractical and the units on hand had to finish the job. Additional fire support by the M113's, a charge by the attacking companies, and heavy fire superiority finally broke the enemy's defense. The companies pressed the attack, forcing the Viet Cong from their bunkers and annihilating those who tried to escape. A sweep of the battle area early the next morning indicated that the enemy had lost the equivalent of a reinforced company. Two U.S. soldiers had died.
Colonel William B. Fulton, the brigade commander, noted that the speed, shock effect, and heavy firepower provided by the personnel carriers, along with supporting artillery, had kept the enemy soldiers in their bunkers until the infantry was literally on top of them. Lieutenant Colonel Edwin W. Chamberlain, Jr., commander of the 3d Battalion, 60th Infantry, stated that since the tracked vehicles proved capable of negotiating more terrain than had been thought possible, there should always be an initial attempt at

PICTURE - TANKS AND ACAV'S SECURE SUPPLY ROUTES IN 25TH INFANTRY DIVISION AREA. Sandbags modify vehicles for security role as movable pillboxes.
TANKS AND ACAV'S SECURE SUPPLY ROUTES IN 25TH INFANTRY DIVISION AREA. Sandbags modify vehicles for security role as movable pillboxes.
mounted movement in order to capitalize on the additional firepower of the vehicular-mounted machine guns.
Mechanized infantry units in the delta were extremely flexible and were used alternately in mechanized, airmobile, and dismounted infantry operations. First and foremost, however, they were mechanized infantry, capitalizing on their vehicular mobility to close with the enemy, then dismounting and assaulting, supported by a base of fire from the vehicles. This is exactly what Company C had done.
Route Security and Convoy Escort
The missions universally shared by armored units throughout Vietnam were furnishing route security and convoy escort. Few tasks were more important than keeping the roads safe and protecting the vehicles, men, and supplies that used them. At the same time, no task was more disliked by armored soldiers. When it was done correctly it could be boring, tedious, and in the minds of many, a waste of time and armored vehicles. When it was done poorly, or when the enemy was determined to oppose it, it was dangerous, disorganized, and, again in the minds of many, a one-way ride to disaster.

General Westmoreland's directive had called for opening the roads, making them safe, and using them. Carrying out the order was a different problem in each area. In one instance in mid-1966 the task became an intricate, large-scale operation that led to battles along Highway 13 and the Minh Thanh Road involving the 1st Squadron, 4th Cavalry. In another situation in the highlands, a significant part of the 4th Infantry Division's armored forces-at first the 1st Squadron, 10th Cavalry, and the 1st Battalion, 69th Armor, and after September 1967 the 2d Squadron, 1st Cavalry -continuously secured roads throughout the division's area of operation in the II Corps Tactical Zone.3 In the first three months of 1967, almost 8,000 vehicles a month under armored protection traversed Highway 19 to Pleiku without incident.
The primary route security technique used in the highlands was to establish strongpoints along the road at critical locations, and each morning have a mounted unit sweep a designated portion of the route. The unit then returned to the strongpoint where it remained on alert, ready to deal with any enemy action in its sector. When forces were insufficient to man strongpoints twenty-four hours a day, each convoy using the road was provided with an escort force, a measure that caused heavy wear on the armored vehicles. Securing roads by using static positions had the disadvantages that the Viet Cong quickly noted them and mined all logical vehicle positions with the result that the protective force soon lost vehicles in the strongpoints. When the 2d Squadron, 1st Cavalry, was attached to the 4th Infantry Division, the division abandoned the strongpoint system in favor of offensive patrolling missions several thousand meters from main routes, a tactic that made a much more effective use of armor.4
Sometimes the security and escort missions were given operational names and continued for six months or more. One such operation, KITTY HAWK in the III Corps Tactical Zone, required a cavalry squadron to secure the Blackhorse Base Camp and the Gia Ray rock quarry, to escort convoys, and to conduct local reconnaissance in force. (See Map 8.) During 1967 the 3d Squadron, 5th

Cavalry, and a squadron from the 11th Armored Cavalry Regiment alternated in this job. Missions such as this were required throughout Vietnam because of constant enemy threats.
Occasionally an escort or security mission was not successful, and usually intensive after action investigation revealed that the unit had been careless. Such was the case with a platoon of Troop K, 11th Armored Cavalry Regiment, in May 1967. When the smoke cleared from a well-planned Viet Cong ambush, the platoon had paid a heavy price: seven ACAV's had each been hit 10 times by antitank weapons and the lone tank had 14 hits. Of forty-four men in the convoy, nearly half were killed and the remainder wounded. Investigation revealed that the road had been cleared that morning by a responsible unit, but the fact that an ambush was set up later proved that it was dangerous to assume that one pass along a road cleared it of enemy forces. In this case there were further errors of omission. No planned platoon action was put into effect when the enemy attacked; no command and control alternatives were provided in the event of a loss of radio communication; no signals or checks were in effect to alert troop headquarters to the platoon's plight; no artillery or air support was planned for the route of march. The lesson from this disaster was that no mission should be considered routine.
Disasters were uncommon to road security missions, but much could be learned from them. On one occasion the law of averages, troop turnover, and the boredom of a routine task caught up with the 3d Squadron, 5th Cavalry, while it was on road security. This incident in late December 1967 illustrates how overconfidence, poor planning, and lack of fire support could combine to strip the cavalry of its inherent advantages. On 22 December the squadron was to assume responsibility for Operation KITTY HAWK. The squadron staff prepared its plans for convoy escort, with convoys scheduled to move on 27 and 31 December. At the last moment, the 3d Squadron's assumption of the KITTY HAWK mission was delayed until 28 December and the 11th Armored Cavalry Regiment performed the escort duty on 27 December. The two-day delay caused the staff of the 3d Squadron, 5th Cavalry, to be less attentive to the second convoy escort mission on the 31st.
On 28 December the 3d Squadron moved into Blackhorse Base Camp, and the next day the squadron operations officer was reminded of the responsibility for the escort on 31 December. Mission requirements were discussed over insecure telephone lines by the staffs of the squadron and the 9th Infantry Division, and were then passed to Troop C, which had the mission. The squadron daily staff

briefing on 30 December did not include a discussion of the escort mission and the squadron commander remained unaware of it. The Troop C commander, familiar with the area, believed the sector to be relatively quiet, a fatal assumption because combat operations had not been conducted in the area for over thirty days. He planned a routine tactical road march to Vung Tau, sixty kilometers to the south, to rendezvous with the convoy at 0900 on 31 December. Two platoon-size elements were to make the march while the troop commander remained at Blackhorse with the third platoon, ready to assist if needed. The platoons were to leave Blackhorse at 0330 on 31 December, moving south on Route 2. One platoon was to stop along Route 2, about a third of the way to Vung Tau, and spend the night running the road back to Blackhorse to prevent enemy interference on the route. The other platoon was to continue to Vung Tau, pick up the convoy, and escort it to Blackhorse. The convoy would be rejoined en route by the platoon conducting roadrunner operations.
The column moved out on time to meet the convoy. The lead platoon, commanded by the 2d Platoon leader, consisted of one tank from the 3d Platoon, 'two ACAV's from the 2d, and the troop command and maintenance vehicles employed as ACAV's. The next platoon, commanded by the 3d Platoon leader, consisted of one tank from the 2d Platoon, two ACAV's from the 3d Platoon, two from the 1st Platoon, and the 1st Platoon's mortar carrier minus its mortar. The tanks, each leading a platoon, intermittently used driving lights and searchlights to illuminate and observe along the sides of the road.
About nine kilometers south of Blackhorse, Route 2 crested a slight rise, ran straight south for two kilometers, and then crested another rise. The sides of the road had been cleared out to about 100 meters. As the lead tank started up the southernmost rise at 0410, the last vehicle in the convoy, the mortar carrier, was leveling off on the straight stretch two kilometers behind. Suddenly a rocket propelled grenade round hit the lead tank, killing the driver and stopping the tank in the middle of the road. An ambush then erupted along the entire two-kilometer stretch of road. A hail of grenades quickly set the remaining vehicles of the lead platoon afire; intense small arms fire killed most of the men riding atop the vehicles. As the trailing platoon leader directed his platoon into a herringbone formation, the mortar carrier was hit by a command detonated mine, exploding mortar ammunition and destroying the carrier. The tank with the last platoon was hit by a rocket grenade round, ran off the road, blew up, and burned. The surprise was so

complete that no organized fire was returned. When individual vehicles attempted to return fire, the enemy, from positions in a deadfall some fifteen meters off the road, concentrated on that one vehicle until it stopped firing. Within ten minutes the fight was over.
At daybreak on the last day of 1967, the devastating results of the ambush were apparent in the battered and burned hulks that lay scattered along the road. Of eleven vehicles, four ACAV's and one tank were destroyed, three ACAV's and one tank severely damaged. The two platoons suffered 42 casualties; apparently none of the enemy was killed or wounded. This costly action showed what could happen on a routine mission in South Vietnam. Indifference to unit integrity, breaches of communication security beforehand, lack of planned fire support, and wide gaps between the vehicles stacked the deck in the enemy's favor. Charged with guarding a convoy, the unit leader failed to appreciate his own unit's vulnerability.
Elsewhere in the III Corps Tactical Zone other U.S. units were performing similar route and convoy security missions. The 3d Squadron, 4th Cavalry, 25th Infantry Division, operated almost

continuously along Route 1 from Saigon to Tay Ninh. The squadron's air cavalry troop worked with it, providing first and last light reconnaissance along main routes. By mid-1967 the squadron was escorting an average of 8,000 vehicles per month. In late summer it began so-called night thrust missions sending out mock convoy escorts at night to test the enemy reaction. After a month-long test without significant enemy action, the 3d Squadron, 4th Cavalry, began escorting night logistical convoys from Saigon to Tay Ninh, a mission that continued through 1967.
Air Cavalry Operations
As a necessary complement to ground armored forces, air cavalry units brought a new dimension to the Vietnam conflict. The first air cavalry unit, the 1st Squadron, 9th Cavalry, 1st Cavalry Division, exploited the concept and literally wrote the book on air cavalry operations. Few other air cavalry units, particularly those with divisional cavalry squadrons, were assigned air cavalry roles at first; instead, they were used to escort airmobile operations-like armed helicopter companies. After the armor study and the assignment of more experienced and innovative commanders, air cavalry troops finally began to operate in air cavalry missions.5 Quite often, however, rotation of commanders, particularly senior commanders, required that lessons be relearned time and again. There was thus a continuing discussion on the proper role and the command of air cavalry units.
In units that properly used air cavalry, operations followed a daily pattern. Upon receipt of information indicating enemy activity, an air reconnaissance was conducted by the troop to determine whether or not further exploitation by ground forces was required. If ground reconnaissance was desirable, the troop commander usually committed his aerorifle platoon. A standby reserve force could be called by the troop commander if the situation required. The air cavalry troop commander controlled all reaction forces until more than one company from a supporting unit was committed. At that time control passed to the commander responsible for the area, and the operation was conducted like a typical ground or airmobile engagement, often with the air cavalry remaining in support. Major General John J. Tolson, Commander, 1st Cavalry

Division, clearly stated his feelings about air cavalry: "I cannot emphasize how valuable this unit [1st Squadron, 9th Cavalry] has been to me as division commander. Over 50 percent of our major contacts have been initiated by actions of this squadron."
To be successful, air cavalry operations had to be swiftly followed by ground or airmobile elements of the division or regiment. Unfortunately in many units with air cavalry, reported leads were frequently not followed up. Consequently, many air cavalry units adopted the unofficial practice of developing leads that could be handled by the air cavalry itself.
In October 1967 two air cavalry squadrons, the 3d and 7th Squadrons, 17th Cavalry, arrived. Because they were the first units of their type to be assigned to U.S. infantry divisions in Vietnam, their integration into the force was accomplished with some difficulty. Most problems reflected a lack of knowledge on the part of the division commander and staff concerning capabilities, limitations, and basic support needs of air cavalry squadrons. There was an unfortunate tendency to use the aircraft for command and control and for transportation in airmobile operations rather than for reconnaissance. At the outset, therefore, air cavalry was not used to best advantage, and there was some misuse. Only after commanders became more aware of the capabilities of their air cavalry squadrons was proper employment achieved, and in some cases the process was slow and painful.6
Other Free World Armor
As early as April 1965, discussions had been held on the deployment to Vietnam of armored units from other nations. Surprisingly, the impetus for such discussion came from Ambassador Maxwell Taylor, and centered on the proposed use of a tank company from New Zealand. At the Honolulu Conference in April 1965 this proposal was disapproved, but by September when the Australian task force arrived an armored personnel carrier troop was included. Equivalent to a reinforced American platoon, the troop was quickly put to work with the U.S. 173d Airborne Brigade. In October free world armor strength increased when the Republic of the Philippines sent a security force of seventeen APC's and two M41 tanks.
The Royal Thai Army forces that arrived in Vietnam in 1967 brought with them an M113 platoon and a cavalry reconnaissance

troop. By 1969 this force had been increased to three cavalry troops and a total of over 660 armor soldiers. The Koreans asked permission to deploy a tank battalion, but the request was disapproved in midsummer 1965 on the grounds that the area was inappropriate for tanks. Later, Korean and American tank-infantry operations in the area enabled the Koreans to acquire APC's on permanent loan from the United States, and these were employed as ACAV's. Finally, in 1968, the Australians sent twenty-six Centurion tanks and an additional cavalry platoon. The Centurions, the only tanks other than U.S. tanks used in Vietnam by the free world forces, had 84-mm. guns and successfully operated east of Saigon near Vung Tau.
Although the armored units were small, they represented a significant proportion of each country's contribution. Their presence, moreover, showed a strong inclination on the part of these countries, particularly those in Asia, to use armored units anywhere as part of a combined arms team. A balanced combat force was their goal regardless of the nature of the terrain.


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