Chapter XI: 
Suoi Cat
(2 December 1966)
The battle of Suoi Cat provides an excellent example of the successful use of armor against the ambush tactics of the Viet Cong. The enemy in Vietnam was not invincible, and a trained outfit frequently took advantage of the mistakes and limitations of the Viet Cong or North Vietnamese Army. This practice applied to the mine threat as well, where the most successful tactic was to attack the man who placed the mine. The 11th Armored Cavalry-the "Blackhorse Regiment" in the forefront of much of the action in the III Corps Tactical Zone, proved again the soundness of battle-tested doctrine and maneuver techniques for tanks and armored cavalry assault vehicles.
The enemy force in this battle was drawn from the 275th Viet Cong Regiment. This regiment was assigned the task of staging an ambush along National Highway 1 in Long Khanh Province just east of Suoi Cat. Order-of-battle experts had put the 275th Viet Cong Regiment well to the northwest, but the unit apparently made its way into the province sometime between late October and late November 1966. Four or five days before the 2 December battle, the 11th Armored Cavalry's intelligence officer received information based on agent reports of "movements north and south of Highway 1" near Suoi Cat and Chua Chan Mountain. This part of Highway 1., a traditional site for ambushes, inevitably came to be known as Ambush Alley. The ambush force, which was later estimated to be a reinforced battalion of the 275th Viet Cong Regiment, spent the latter part of November reconnoitering the ambush site and preparing positions complete with overhead protection. In typical Viet Cong fashion, maximum use was made of local cover, and withdrawal routes were plotted, principally to the south.
On 1 December 1966, Troop B, 1st Squadron, 11th Armored Cavalry, minus its 3d Platoon but reinforced by a platoon of tanks from the squadron's tank company, took over the security of the rock quarry at Gia Ray. In December, the Troop B commander sent a convoy to the regimental base camp near Xuan Loc to obtain supplies. The two tanks, three armored cavalry assault vehicles, and two

2 1/2-ton trucks reached the base camp without incident. The supplies were loaded, and the group headed for Gia Ray at 1600 hours. The tank platoon leader, 1st Lieutenant Wilbert Radosevich, was the convoy commander and arranged his vehicles in the following order: tank, two armored cavalry assault vehicles (ACAV's), two supply trucks, ACAV, tank. A helicopter gunship on the convoy's radio frequency and a forward air controller were covering overhead. At Suoi Cat the convoy commander switched back from the squadron's radio net to the B Troop net as he cleared Chua Chan Mountain, which often distorted communications between Gia Ray and the regimental base. Since the 1st Squadron maintained a relay station on top of Chua Chan, the convoy commander's communications setup was excellent.
As the convoy moved east out of Suoi Cat, Lieutenant Radosevich noticed an ominous lack of activity along the road: no men or women, no children, no dogs. About two kilometers from the hamlet, the lieutenant turned in the commander's hatch and accidentally tripped the turret override, causing the main gun to swing to the right. Apparently seeing this movement, an enemy soldier prematurely detonated a mine about ten meters ahead of Lieutenant Radosevich's tank. The fight was on. The convoy commander, wounded by mine fragments, directed the odd numbered vehicles to fire to the left of the road and the even numbered vehicles to fire to the right, thereby establishing the herringbone formation. He also sent word to B Troop that the convoy was under attack; relief from several directions was on the way. Though hit repeatedly with recoilless rifle and rocket rounds, the combat vehicles kept moving through the kill zone and escorted the two trucks to safety in the direction of Gia Ray.
The Troop B commander, Captain John R. Landry, led a relief column of two tanks and three armored cavalry assault vehicles south out of Gia Ray toward the ambush. They were joined at the junction of Highways 1 and 333 by ACAV's from Captain Landry's 2d Platoon and plunged into the fray. The 2d Platoon suffered some fourteen nonfatal casualties from Viet Cong grenades as it neared the ambush site, but it herringboned its way into the battle with deadly effect. Elements of Company D took off from the regimental base seven minutes after the first report of contact, followed closely by Troop C and the howitzer battery. Ten minutes later, Troop A was on the way. Meanwhile, the helicopter gunship was making firing runs, and requests for artillery fire and air strikes had been sent. The tanks of Company D and the ACAV's of Troop C, in turn, raked the ambush site. Troop C moved east down Highway 1 to cover possible Viet Cong withdrawal routes. Troop A arrived just as some of the Viet Cong were attempting to leave their positions. Fifteen of the enemy were cut down before they could get away. The battle which began about 1640

PICTURE: M48 Tanks Halted in Herringbone Formation
hours was over by 1750, but sporadic fire from the Viet Cong continued until 1950. In an attempt to seal off escape routes, artillery and AC-47 "Spook" ships were used throughout the night. The Viet Cong lost at least ninety-nine men and suffered a stunning defeat. One U.S. soldier, a sergeant in the 27th Engineer Battalion, lost his life in the battle, and there were twenty-two other casualties in the Blackhorse Regiment.

The Viet Cong commander had selected the small resupply convoy as a target, perhaps believing that it could be easily overwhelmed. Normally quite skillful in the planning and execution of ambushes, the enemy at Suoi Cat committed a number of costly errors. The premature detonation of the mine was the first mistake. Although the killing zone was covered by light and heavy machine guns, 60-mm. mortars, small arms, at least one recoilless rifle, and an undetermined number of rocket-propelled grenade launchers, the Viet Cong were unable to achieve fire superiority in the first critical moments of the action. Having failed to stop either the lead or the rear tank, they were furthermore unable to cope with the ACAV's. The most disastrous mistake made by the enemy leader was to spring the ambush when U.S. relief units were so close. Within four minutes the tank platoon had reached the killing zone, and Troop B's 2d Platoon arrived in seven minutes. If the Viet Cong commander had been familiar with the potential of the ACAV in combat, very likely he would not have positioned his men so close to the road. Whatever the exact reasoning behind the location of the ambush force, it was exposed to the considerable and effective fire of ACAV machine gunners and grenadiers.
The Viet Cong positions, although out of range of the eight-inch howitzers at Xuan Loc, were soon taken under fire by the fast moving artillerymen of the 1st Squadron's self-propelled 105-mm. howitzer battery. The ability of the artillery to move rapidly from one position to another and to set up within range apparently was not taken into account by the Viet Cong ambush planner. The squadron's howitzer battery was joined at Suoi Cat by Battery B, 2d Battalion, 35th Artillery, a 155-mm. self-propelled unit. Some 1,700 rounds were fired by these two batteries during the fight.
By the time the Company D and Troop C reinforcements arrived, the Viet Cong commander realized that he had failed in his mission and that he must withdraw. Enemy fire was intensified before the appearance of A Troop to allow the Viet Cong to disengage and move to withdrawal routes. The timing of this move was poor, however, as the Blackhorse troopers caught many of the Viet Cong in the act of withdrawing.
Enemy mines, such as the command-detonated device used at Suoi Cat, were a constant threat to our forces. Although the U.S. Army did employ claymore mines as a weapon, most of its efforts in this area were concentrated on defense. Enemy mines and booby traps caused approximately 70 percent of the vehicle losses and 20 percent of the casualties. The enemy employed "nuisance mining," that is, scattering mines throughout an area rather than in well-defined minefields, on a scale never before encountered by U.S. forces. Mines and booby traps were usually installed at night by

trained personnel who had detailed knowledge of the terrain. Through ingenious techniques in mine warfare, the Viet Cong successfully substituted mines and booby traps for artillery. Instead of conventional minefields covered by fire, the enemy hindered or prevented the use of supply roads and inhibited off-the-road operations by planting explosive devices in indiscriminate patterns. While he benefited directly by causing combat casualties, vehicle losses, and delays in tactical operations, equally important was the psychological effect. Just the knowledge that a mine or booby trap could be placed anywhere slowed combat operations and forced allied troops to clear almost the entire Vietnam road net every day.

In response, an Army-wide concentrated effort in strategic and tactical planning, research and analysis, and materiel development was focused on countermeasures for mines and booby traps. The Mine Warfare Center of the Headquarters, United States Army, Vietnam (USAKV), conducted an extensive study of the Viet Cong and North Vietnamese mining operations, techniques, and ordnance. Major Walter C. Bell, the chief of the center, published a report, "Mine Warfare in Vietnam," as a guide for units in the field. Although he found that Viet Cong and North Vietnamese techniques varied from place to place, Major Bell was able to make some generalizations. The enemy did not use the traditional minefields of previous wars. He laid protective fields around the more permanent base camps but with no pattern, and the mines were certain to be booby-trapped. Major Bell also discovered that the enemy tended to mine the same sectors of roads repeatedly.
Major Bell divided the mining problem into three major categories: road mining, off-road antivehicular mining, and antipersonnel mining. Most U.S. mine casualties occurred during road clearing operations. Heavy losses coupled with the need to clear many kilometers of road every day put a strain on the engineer and combat troop effort. Off-road mines caused more damage to armored vehicles than road mining did. Little used trails and tracks, open fields, jungles, and even avenues that were difficult for vehicles to use were mined. The antipersonnel mines or booby traps were ingeniously rigged devices, set in unusual locations to trap the individual soldier. Such devices, normally made from materials at hand, were used on a massive scale. Virtually every enemy position was encircled or infested with them. From an extensive analysis of the techniques used by the enemy in each of the four corps tactical zones, the Mine Warfare Center marked on a map the areas where mining activity was heavy and qualified each area by indicating the most common type of mine there. Armed with this knowledge, the tactical commanders and individual soldiers were able to reduce U.S. casualties.
In the III Corps Tactical Zone, the Viet Cong seemed to adjust

their mining pattern according to U.S. tactical operations, rather than following a preconceived plan. During periods when U.S. and allied activity was high, there was a substantial increase in the Viet Cong mining efforts. Roads and off-road tracked vehicle paths were the main targets. The problem facing the 11th Armored Cavalry in this area became one of inhibiting the enemy's road-mining activities. The regiment also learned that the mining and the setting of booby traps was largely the work of Viet Cong local forces rather than larger Viet Cong and North Vietnamese Army units.
The Army took extensive steps to educate all subordinate commands concerning mines and booby traps. Information which defined the mine threat in various areas was passed down through channels. Units prepared monthly reports that outlined mine warfare incidents, the types of mines or booby traps encountered, and their locations. The Mine Warfare Center distributed notes to all major USARV units to inform them of various techniques that might be useful in countering the explosive devices.
A further effort to educate troops was made by the Combined Intelligence Center, Vietnam. "Viet Cong/North Vietnamese Army Employment of Mines and Booby Traps" described all of the mines and booby traps used by the enemy in Vietnam. Included were foreign mines and fuzing devices, plus expedient mines and ingenious fuzing devices and trip wires used to detonate booby traps. All combat units used the documents and the experiences of division personnel to conduct mine warfare training for new arrivals.
U.S. forces unwittingly furnished many of the items from which the enemy fashioned mines and booby traps. Explosive material. came from dud rounds and other ordnance lost or discarded by U.S. troop units. Empty C-ration cans and used batteries were prime components of Viet Cong mines. Field commanders conducted a constant antilitter campaign. Control of ammunition and policing of defensive positions were stressed.
Using the Rome plow in land clearing operations helped to reduce command-detonated mine incidents. Removing all vegetation from the sides of roads and around base camps eliminated enemy cover. The paving of roads proved to be one of the most effective means to counter enemy mines, since holes in the asphalt were difficult to dig and easy to identify. A good example was heavily mined Route I in Quang Ngai Province. Although culverts were still destroyed by the enemy, there were no mining incidents after the road was paved. A similar technique for unpaved roads was the daily use of oil or peneprime over an area previously cleared of mines. Enemy attempts to mine the road were then readily apparent. Another effective countermeasure used by many units in Vietnam was to encourage local citizens to report the location of mines in return for a cash reward. In

PICTURE: Engineer Mine Clearing Team

1968, through this volunteer informant program, 103,521 pieces of ordnance that could have been used as mines and booby traps were located. Trained dogs were also effective in detecting these devices. In one test involving 131 road clearing missions, 157 area searches, and 2 village searches, the dogs found 19 mines and 33 booby traps.
Kits were developed for armored personnel carriers to provide supplemental armor for the hull bottom and to relocate and strengthen the fuel line. One armored personnel carrier on which the new armor kit was installed hit a twenty-pound mine with no casualties among the men on board.
Generally, mine detectors designed to locate metallic mines or minute pieces of metal were not effective. One method which combated the difficulty of detecting tiny metal detonators in dirt roads sprinkled with artillery fragments was to use the same minesweep team every day. The men became so familiar with the road that they were able to spot minor changes in the surface or the surrounding area. The majority of mines found were detected visually and destroyed with explosives in place.
Still being developed are various hand-held infrared detectors and others for use in helicopters and vehicles. Experiments were conducted

to induce current in mine detonator wiring using radio frequencies. However, these experiments were unsuccessful and were terminated. A need for better protection of troops against the enemy's mine threat prompted the Combat Developments Command to consider mine protection in future vehicle developments. In addition, the U.S. Army Materiel Command continued its efforts to develop energy absorbing systems to reduce the shock of mine explosions.

The ENSURE 202 Tank-Mounted Expendable Mine Roller was tried in Vietnam as a mine-detonating device. Designed to exert high ground pressure without crushing roads and bridges, it was attached to a medium tank. Like the many rollers used in Vietnam and earlier, the problem was to survive the mine it detonated.
Tactical operations, including ambushing and patrolling, were designed to hit at the enemy's mining efforts. Countermine activities were oriented toward finding mines after they had been positioned and toward improving the ability of personnel and vehicles to survive an explosion. In Vietnam the U.S. forces attacked the source of the problem. The most useful technique was frequent ambush patrols in areas repeatedly mined. At times observation towers were constructed on routes in the vicinity. A reconnaissance in force was often conducted by cavalry units ten or fifteen minutes after a mine sweep to surprise the enemy who would lay mines behind the team. One unit in the III Corps Tactical Zone made a detailed study of enemy roadmining patterns. The analysis showed that 50 percent of such activity in the area of operations was concentrated in four sectors of road having a total length of about 41A kilometers. Once the problem areas were isolated, sensor fields were installed and ambush patrol activity was increased. Artillery concentrations were plotted, night aircraft equipped with infrared lights were put on alert, and night observation devices were positioned so that the unit could respond to sensor activations and patrol sightings. After only one month the results were conclusive. The four road sectors, which had previously experienced fifty-six mining incidents per month, had only fifteen incidents during the test month. One sector went from fifteen to one.
In addition to tactics against enemy mining, countermeasures for ambushes were also developed. The objective of the herringbone technique, used so successfully at the battle of Suoi Cat, was to concentrate a formation of combat vehicles "sufficiently to achieve overwhelming firepower to the flanks while maintaining sufficient dispersion to force the enemy to employ aimed fire." An armored column could also herringbone its way down a line of march by applying the leapfrog technique. The first platoon halted in the herringbone pattern. The second platoon passed through the first and assumed the herringbone pattern. The third continued on through, and the process was repeated until a suspicious or particularly dangerous area

PICTURE: ENSURE 202  Roller on M48 Tank
had been crossed. If contact was made, the herringbone permitted the commander to "fix and hold an entire ambushing force," as in the case of Suoi Cat.

Naturally, the mere execution of the herringbone formation did not guarantee success in a counterambush effort. The shock of the initial enemy volley had to be countered with a withering blast of return fire even more shocking to the enemy soldiers. The 11th Armored Cavalry's counterambush training emphasized that gunners on odd numbered vehicles were to fire to the left; those on even numbered vehicles were to fire to the right. If there were no visible targets to engage, the .50-caliber gunners on the armored cavalry assault vehicles were to begin raking fire at fifty meters and the M60 gunners at twenty-five meters, and the men acting as grenadiers were to start heaving grenades over the sides of the vehicles. The ACAV's carried enough ammunition for about ten minutes of almost continuous firing. The inseparable factors of command and control played an especially vital role in counterambush tactics. The herringbone formation enabled a commander to move around his command, provide his men with more ammunition, and remove any wounded from the ambush zone. The herringbone pattern was useful as a base of fire

while other elements maneuvered against the enemy and allowed the unit to communicate with the "outside world" and let those who could help him know that he had a problem. In the case of Suoi Cat, the lieutenant could contact his squadron, B Troop, the gunship, and the forward air controller. Either the gunship or the forward air controller could have acted as an airborne relay if necessary and could have provided invaluable route reconnaissance ahead of the convoy. Finally, the training of the entire squadron as a team and its dedication to the offense provided the extra drive and co-ordination needed to get the relief column on the way. Lieutenant Radosevich's small group gave a fine account of themselves; however, the timely arrival of other elements of the squadron carried the day.
The success of U.S. armor formations in Vietnam was the result of many factors. The herringbone and the maneuver aspects of the counterambush drill were the most obvious. Support by artillery, tactical air fighters, and helicopter gunships was less obvious but equally effective. Combined, these elements often neutralized the effectiveness  of the enemy ambush.
The mining problem in Vietnam was never solved to the extent that operations could be conducted without provisions for mine detection. It was, however, reduced considerably by a combination of old and new techniques. The mine dog and new mine detectors were adaptations of earlier techniques, while the most significant innovation was the concept of engaging the minelayer before the mine was planted. This concept, to strike the problem at its source, was one of the most fundamental aspects of the war.

page created 15 December 2001

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