(General Hieu, as III Corps Deputy Commander/Operations, was undoubtedly the main player behind-the-scenes in this Iron Triangle Campaign. In this campaign, both sides threw in all their strength to wrestle against each other at corps level with complete infantry, armor, artillery, air force, and anti-aircraft artillery: III Corps on ARVN’s side and 301st Corps on NVA‘s side. Colonel Le Gro, the author of this book excerpt, was the senior intelligence officer G2/DAO. – Tin Nguyen, 11/22/2005)
A glance at the map shows the strategic location of the Iron Triangle. Bounded on the north by the jungle and overgrown rubber plantations of the Long Nguyen, it was enclosed on the west by the Saigon River and on the east by the smaller but unaffordable obstacle of the Thi Thinh River. The Thi Thinh joined the Saigon River near Phu Hoa, at the southern apex of the Triangle, 7 miles from Phu Cuong. Phu Cuong itself, the capital of Binh Duong Province, was an important industrial and farming center and contained the ARVN Engineer School. It was linked by a major highway with the large ARVN base at Phu Loi (called Lam Son) and, farther east, with Bien Hoa. Lying as it did in the center of the Saigon River corridor, at the junction of Routes 13 and 1A, and only 10 miles from the outskirts of Saigon, Phu Cuong was vital to the defense of Saigon.
The terrain within the Iron Triangle was flat, almost featureless, and covered by dense brush and undergrowth. The clearings, especially in the northern part, were thick with elephant grass, higher than a man's head. The surface was scarred by countless bomb and shell craters so that vehicular movement off the narrow, rough dirt roads was nearly impossible. Even tracked vehicles had difficulty. A vast network of tunnels and trenches, most of them caved-in and abandoned, laced this ground that had been the scene of battles since the early days of the second Indochina war.
A weak string of three ARVN outposts protected the northern edge of the Triangle, from Rach Bap on the west, close by the Saigon River, along local Route 7 (TL-7B) to An Dien on the Thi Thinh River opposite Ben Cat. Each of these outposts, including Base 82, which was midway between Rach Bap and An Dien, was manned by a company of the 321st RF Battalion. Another country road passed by the Rach Bap outpost: local Route 14 (LTL-14) which generally paralleled the Saigon River from Tri Tam, through Rach Bap, and veered to the southeast through the Triangle, crossing the Thi Thinh River before it joined Highway 13 (QL13) north of Phu Cuong. The NVA had blown the bridge on Route 14 over the Thi Thinh a few weeks earlier, but the stream could be spanned by pontoon sections. About midway between Rach Bap and the Thi Thinh crossing of Route 14, the ARVN had another small firebase.
Frequent sweeps and some semi-fixed defensive positions north of Cu Chi manned by the ARVN 25th Division and Hau Nghia Regional Forces screened the western flank of the Triangle, but enemy resistance in the Ho Bo woods, opposite Rach Bap, and the formidable obstacle of the Saigon River, as well as a lack of resources, limited the influence that the 25th could exert on the situation within the Triangle.
The ARVN was strong with infantry, armor, and mutually supporting fire bases and outposts in Ben Cat District east of the Thi Thinh boundary of the Triangle, but only one bridge, a weak span, connected the district town and the Triangle hamlet of An Dien. Such was the situation on the eve of the initiation of the strategic raids campaign in western Binh Duong Province. As mentioned earlier, this was a coordinated attack, with the 9th NVA Division conducting the main effort in the west, while the 7th NVA attacked in the east against ARVN positions along Highway 1A near Phu Giao. The distances between the two thrusts were too great, concurrent attention of the III Corps commander however, to provide for mutual support, and the ARVN III Corps was able to deal with separate operations. For these reasons, although they occurred simultaneously and demanded the concurrent attention of the III Corps commander and his staff, they can best be described sequentially, beginning first with the Iron Triangle attack of the 9th NVA Division.
Iron Triangle Attack
The attack began with heavy artillery, rocket, and mortar concentrations falling on Rach Bap, Base 82, and An Dien on the morning of 16 May. The RF company at Base 82 abandoned its bunkers, many of which had collapsed under the weight of the bombardment, late that afternoon. Rach Bap held out until about 0300 the following morning, its surviving defenders withdrawing in the direction of An Dien. The fighting was fierce in An Dien on the 16th, but by the night of 17 May, NVA forces held the flattened village and its defenses. Remnants of an RF battalion, however, held the western end of the Thi Thinh bridge in a shallow blocking position, while the eastern end, by Ben Cat, was secured by ARVN forces. The enemy dug in around An Dien but was unable to dislodge the RF positions at the bridge.
Two infantry regiments of the 9th NVA Division, with about ten T-54 and PT-76 tanks, were employed against the dispersed 321st RF Battalion. The 272d Regiment overran Rach Bap and continued the attack south into the Triangle along Route 14, while the 95C Regiment attacked Base 82 and An Dien. The 271st Regiment was held in reserve.
The RVNAF at Ben Cat were unable to counterattack the NVA immediately at An Dien because the bridgehead held by the RF was too shallow to protect the crossing of any large forces, but General Thuan quickly began reinforcing Ben Cat. Task Force 318 arrived in Ben Cat District on the afternoon of the 16th and on the 17th began reinforcing the RF holding the bridge and moving against the enemy's blocking positions west of the bridgehead. The weakness of the ARVN bridgehead and the strength of the enemy positions in An Dien, which included antitank guns and tanks, made it impractical to send any armor of the 318th across the An Dien bridge at this time.
Meanwhile, the 322d Task Force moved from Tay Ninh Province to Phu Cuong and was ordered to prepare to attack into the Triangle along Route 14 (LTL-14) in order to oppose the 272d Regiment, which was moving south from Rach Rap.
VNAF aerial observers and photography on 17 May revealed two T-54 tanks inside Base 82, which VNAF fighter-bombers destroyed the next day, and four more in the An Dien base. Initial negative reactions at ARVN III Corps Headquarters to the seemingly hasty, if not unwarranted, withdrawal of the RF companies from their positions softened somewhat when the size and composition of the enemy force was revealed.
Six months would pass before the situation existing before 16 May would be restored along the northern edge of the Iron Triangle. The campaign was never officially divided as such, but major operations fell into four distinct phases. In the first, 16-17 May, the NVA had captured the northern edge of the Triangle and launched a major column into the center of this strategic approach to Phu Cuong. In the second phase, 18 May to 5 June, the ARVN counterattacked and regained control of An Dien. Four months later, on 4 October, ARVN troops concluded the third phase by reoccupying the devastated wasteland that was once Base 82. Finally, on 20 November ARVN infantry re-entered Rach Bap, concluding the last phase of the 1974 Iron Triangle campaign.
An Dien Counterattack
General Thuan greatly underestimated the strength and tenacity with which the 9th NVA Division would defend An Dien, although he had accurate intelligence concerning the size, composition, and location of the enemy. His initial plans for the second phase, which proved unrealistic, called for virtually simultaneous recapture of the three lost bases by about 22 May. Perhaps the remarkable successes his corps troops had in repulsing the NVA 7th Division attacks on the Phu Giao front had given him this unwarranted overconfidence.
Except for the few ARVN infantry and engineers that were thrown across the Thi Thinh River to reinforce the An Dien bridgehead, the first major ARVN unit to move into the Triangle was a battalion of the 43d Infantry, 18th ARVN Division, which crossed on Route 14 north of Phu Cuong. Shortly reinforced by the rest of the regiment, this element, followed by the 322d Armored Task Force, was to attack Rach Bap and Base 82. Meanwhile, the 318th Task Force would cross the An Dien Bridge, pass through An Dien, and proceed to Base 82. Three Ranger battalions attacking south out of Lai Khe were to strike Base 82 from the north. None of this worked as planned. The 43d Infantry became stalled after advancing only four or five kilometers north. Then, the tracked vehicles of the 322d Task Force found the going extremely slow in the dense brush and cratered terrain. General Thuan, concerned lest this armored force become bogged down and have a bridge blown behind it, ordered its withdrawal. He discovered, meanwhile, that the An Dien bridge had been seriously weakened by enemy artillery (including AT-3 missiles) and would not support the tanks of the 318th Task Force. Under enemy observation and, sporadically, heavy mortar and artillery fire, ARVN combat engineers attempted to repair the bridge. Casualties mounted, and the work progressed very slowly. About the same time, the 7th Ranger Group, with three battalions, moved southwest out of Lai Khe, crossed the Thi Thinh River and advanced on Base 82. The Rangers were immediately opposed in the thick jungle and rubber plantation by the dug-in troops of the NVA 9th Division, and their attack stalled well short of the objective.
While III Corps was experiencing great difficulty getting moving, it was pounding An Dien with heavy artillery fire. The North Vietnamese responded in kind against ARVN batteries and the stalled Ranger and infantry columns and sent sappers into an RF command post just south of Ben Cat, where they destroyed a 105-mm. howitzer and routed most of the small garrison.
The VNAF, meanwhile, gave only limited support. NVA antiaircraft artillery and SA-7 defenses were plentiful in the area, forcing VNAF aircraft to high altitudes. On 24 May, an armored cavalry squadron of the 25th ARVN Division launched a diversionary attack from Go Dau Ha east toward the Boi Loi Woods. General Thuan's purpose was to cause enough of a threat here to prevent the 9th NVA Division from committing its reserve, the 271st Regiment, against either the 318th or the 322d Task Forces. By the 25th, the armored cavalry squadron had passed Suoi Cau without encountering any resistance, and another supporting maneuver began with two battalions of the 50th Infantry, ARVN 25th Division, moving north from Phu Hoa along the west bank of the Saigon River.
On 25 May, General Thuan met with the commander of the 18th ARVN Division, Brig. Gen. Le Minh Dao, and with the commander of the 3d Armored Brigade, Brig. Gen. Tran Quang Khoi, to coordinate the following morning's attack. At that time, the 43d Regiment was about seven kilometers south of An Dien, about to attack north, while the 3d Armored Brigade was preparing to send a cavalry squadron and a Ranger battalion across the An Dien bridge.
Although the enemy's heavy mortar and artillery fire had so weakened the bridge at An Dien that the cavalry could not follow the Rangers, by nightfall the 64th Ranger Battalion was dug in on the eastern edge of An Dien Village. The 43d Regiment was again ordered to resume the attack north, and the 7th Ranger Group, coming down from Lai Khe, was ordered to take Base 82 by night attack on 27 May. Because no progress was made General Thuan on 28 May decided to try a fresh approach. First, he turned the operation over to General Dao, told him to move his 52d Regiment over from Phu Giao, gave him operational command of the 7th Ranger Group, which was still north of Base 82, and attached to Dao's 18th Division a reinforced squadron of the 3d Armored Brigade. Since it would take two days to relieve the 52d Regiment on the Phu Giao front and move it into position at Ben Cat, the new operation was scheduled for 30 May. Delays in the relief and movement forced General Dao to set the date ahead to 1 June.
With the Rangers still holding the shallow bridgehead opposite Ben Cat and the 43d Regiment making slow progress attacking the dug-in 272d NVA Regiment south of An Dien, General Dao sent the 2d Battalion, 52d Regiment, across the Thi Thinh River on an assault bridge south of Ben Cat on 1 June. Once across, it turned north to attack the defenses of the 95C NVA Regiment in An Dien. Meanwhile, the reconnaissance company and an infantry company from the 18th Division crossed the An Dien bridge and advanced toward the village. Casualties on both sides were heavy that day in An Dien as the commander of the ARVN 52d Regiment committed his 1st Battalion behind the 2d. The 9th NVA Division responded by assaulting the ARVN infantry that night with infantry and at least 10 tanks. The two battalions of the 52d held their positions and were reinforced by the 3d Battalion the next afternoon. Meanwhile, ARVN combat engineers were clearing the road past the An Dien bridge. Working at night with flashlights to avoid enemy observation and fire, they removed 38 antitank mines from the route of advance.
Weakened by casualties, the 52d Infantry made very little progress on 2 and 3 June, and the 43d Regiment was still being blocked by the NVA 272d Regiment. General Dao then ordered his 48th Infantry across the Thi Thinh south of Ben Cat, to pass through the 52d and take An Dien. While the NVA artillery continued to pound ARVN positions, two battalions of the 48th crossed into the Iron Triangle on the night of 2-3 June.
The fighting at An Dien was especially fierce on 3 June as the NVA used tanks against ARVN infantry. Armed with light antitank weapons, ARVN infantry knocked out at least four enemy tanks in the final day of the battle. On 4 June, troops of the 18th ARVN Division finally entered An Dien, and on the 5th overran the last position of the NVA's 95C Regiment, which had since been reinforced by elements of the 9th NVA Division's 271st Regiment. On the morning of the 5th, two battalions of the 48th and two of the 52d were holding An Dien, bracing for a counterattack. One Ranger battalion was in a blocking position north of the destroyed village, while another secured the An Dien bridge. The 43d Regiment was still stalled by the NVA's 272d Regiment's defenses south of An Dien. The 7th Ranger Group had not been able to advance toward Base 82 from the north, and a new major ARVN attack would be required to advance past the positions held in and around An Dien .
NVA soldiers captured by the 18th ARVN Division in An Dien told of horrendous losses in the three battalions - the 7th, 8th, and 9th - of the 95C Regiment. Fourteen surviving members of the 9th Battalion were captured when the last strongpoint fell on 5 June. They said that casualties in the 8th and 9th Battalions between 16 May and 4 June were 65 percent, that a company of the 7th Battalion had only one man left, that a company of the 8th Battalion was totally destroyed, and that the 9th Battalion lost two complete companies. These accounts were confirmed by the large number of bodies left on the battlefield and by the quantity of weapons and equipment captured. ARVN losses were substantial, but none of its units were decimated as were those of the 9th NVA Division. Well over 100 ARVN soldiers had been killed in action, and the hospitals held over 200 wounded from An Dien, while 200 more suffered light wounds not requiring evacuation.
The expected NVA counterattack came on the night of 5-6 June as two battalions of the 271st Regiment, 9th NVA Division, supported by up to 14 tanks, attacked from two directions. The ARVN 18th Division held and its infantrymen knocked out 5 tanks and damaged 5 others.
The second phase of the Iron Triangle campaign was over with the recapture of An Dien, and General Thuan was anxious to get the attack moving again toward Base 82 and Rach Bap. Although the An Dien bridge would soon be in condition to carry the tanks of the 318th Task Force - one company of armored personnel carriers had already crossed into An Dien - a knocked-out T-54 tank blocked the narrow road from the bridge into An Dien. Swampy ground on each side prevented bypassing the tank, and it had to be blown off the road with demolitions. ARVN combat engineers were laboring at this task while infantrymen of the 18th Division were holding the perimeter around An Dien.
The first of several attempts during the third phase to retake Base 82 began on 7 June 1974 when the 318th Task Force finally brought its tanks across the Thi Thinh River and passed through the 18th Division position in An Dien. While the 52d Infantry of the 18th Division remained in reserve holding the An Dien perimeter, two battalions of the 48th Infantry moved south and west to protect the southern flank of Task Force 318 as it attacked along Route 7 (TL-7B) toward Base 82. To the south, the 43d Regiment maintained contact with the NVA 272d Regiment. Meanwhile, the 9th NVA Division had withdrawn the remnants of the 95C Regiment from action and placed its 271st Regiment at Base 82, where it prepared deep, mutually supporting defensive positions. Clearly indicating its resolve to conduct a determined defense along Route 7 in the Iron Triangle, COSVN sent the 141st Regiment of the 7th NVA Division south from its position along Highway 13, north of Lai Khe, to reinforce the 9th Division north of Base 82. The 9th Division meanwhile began shifting the 272d Regiment north from the southern part of the Iron Triangle to assist in the defense of Base 82 and Rach Bap.
The wet summer monsoon had arrived in Binh Duong Province. Rains and low cloud cover further reduced the effectiveness of VNAF's support of the attack. A dense rubber plantation northwest of Base 82 provided excellent concealment for supporting defensive positions and observation of local Route 7, the only avenue of approach available for ARVN armor. Dense brush covered the southern approaches to the base and concealed more enemy supporting and reserve positions. The only fairly open terrain was on either side of Route 7 where high grass offered no concealment to the ARVN column but reduced the visibility of ARVN tanks and infantry to a few meters. Furthermore, this approach was under the observed fire of the 9th NVA Division's supporting artillery, which included 120-mm. mortars, 122-mm. howitzers, 105-mm. howitzers, and 85-mm. field guns. Infantry mortars, 82-mm. and 61-mm., added to the indirect fire, and, in addition to the B-41 antitank grenade launchers carried in great numbers by the NVA infantry, NVA soldiers were amply equipped with the new Soviet 82-mm. recoilless gun, a superb weapon.
By the evening of 8 June, Task Force 318 reached its first objective, Hill 25, about 1,000 meters short of Base 82. There it fought a battalion of the NVA 271st Infantry, killing 30 and capturing 10 while taking light casualties. The prospects seemed bright for recapturing Base 82 by the following day, and General Thuan told General Dao of the 18th ARVN Division that Rach Bap should be taken by 15 June. But on 10 June Task Force 318, advancing very slowly in two columns, one north of Route 7 and one south, was struck by a battalion of the NVA 271st Infantry supported by four tanks and a heavy concentration of mortar, howitzer, and rocket fire. Four of Task Force 318's tanks and one of its personnel carriers were knocked out but personnel losses were light. By nightfall only 200 meters had been gained, the enemy's minefields and 82-mm. recoilless guns having stopped the task force 800 meters short of Base 82.
No progress was made on 11 June, but ARVN artillery and VNAF pounded the base. Antiaircraft fire was intense and kept the VNAF fighter-bombers above their most effective attack altitudes. Meanwhile, General Thuan, determined to get the attack moving again, directed Brig. Gen. Khoi, commander of the 3d Armored Brigade, to assemble the 315th Task Force at Ben Cat and send it across the Thi Thinh to reinforce the attack. The 315th was to move southwest and attack Base 82 from the south, while the 318th continued its frontal assault. Farther south, another change was taking place. Detecting that all but one of the NVA's 272d Regiment's battalions had moved north toward Route 7, General Dao left only one of his 43d Infantry battalions in the Phu Thu area, placing the balance of the regiment in reserve.
By noon on 12 June, the 315th Task Force had reached a position about 1,600 meters southeast of Base 82. At this point, General Dao changed the original concept of a two-pronged attack from the east and south. As soon as the 315th was ready to attack, he would withdraw the 318th to defend the eastern approaches to Ben Cat that had been weakened by the commitment of the 315th against Base 82. Thick brush, rough terrain, and accurate enemy artillery fire prevented the 315th from making any gains on 13 June. In fact, as the 318th withdrew from contact, it left positions much closer to the objective than those reached by the 315th.
In another change in plans, General Dao proposed to General Thuan that two battalions each from the 43d and 52d Regiments take over the attack role, while the 315th remained in its defensive perimeter southeast of Base 82. The infantry battalions would move into the rubber plantation and attack from the north. General Thuan agreed and left for JGS headquarters to ask for a new ammunition allocation for the attack. He returned to his headquarters in ill humor, for General Khuyen, the RVNAF Chief of Logistics, was unable to satisfy this request.
By 15 June, the two leading ARVN 43d Infantry battalions, one of which was attempting to swing north of Base 82 from An Dien, had made very little headway against strong resistance and heavy enemy artillery fire. In contacts south of Route 7 on the 17th, prisoners of war were taken from the 272d Regiment, soldiers who had recently arrived in South Vietnam and had been assigned to the 272d for only three days before their capture. ARVN casualties continued to mount, troops were desperately fatigued, artillery support was too severely rationed, and the weather all but eliminated effective air support. On 21 June, General Thuan ordered a halt in the attempt to take Base 82, while a new approach, better supported by artillery fire, could be devised. Consideration was also given to replacing the 18th Division, whose troops had been in heavy combat for a month, with the 5th Division.
Instead of relieving the 18th, General Thuan decided to try his armor again. Holding the infantry in position, he sent the 318th and 322d Task Forces back into the Triangle, one north of Route 7, the other generally along the road. The enemy's antitank defenses, primarily employing the 82-mm. recoilless gun, stopped the attack once again, destroying 13 personnel carriers and 11 M-48 tanks between 27 June and 1 July, even though ARVN artillery and the VNAF supported the attack with 43,000 rounds and 250 sorties. The tired infantrymen of the 43d Regiment tried once again to take Base 82 from the south on 1 July but got nowhere.
On 2 July, General Thuan finally decided to relieve the 18th Division and replace it with the 5th. The armored task forces would be withdrawn for rest and refitting. General Thuan allowed his commanders ten days to complete the relief; he wanted it done gradually and expertly so that constant pressure could be maintained against the enemy. In order not to weaken the 5th Division's defenses north of Lai Khe, elements of the 18th Division's 52d Regiment, which had seen little action, and two battalions of the 25th Division's 50th Infantry were attached to the 5th Division in the Iron Triangle. The relief was accomplished on schedule, and a relative calm settled over the Base 82 battleground. The 9th NVA Division also made adjustments during the last part of June and the first weeks of July. While the 272d Regiment retained defensive positions in the southern part of the Iron Triangle, the 95C Regiment, refitted and with fresh replacements, returned to the Base 82 area and assumed responsibility for its defense. The third regiment of the 9th NVA Division, the 271st, held defensive positions in the Base 82 area, primarily to the north and northeast. Meanwhile, the 141st Regiment of the 7th NVA Division returned to its normal area of operations north of Lai Khe, and artillery support for the 9th NVA Division was assigned to the 42d NVA Artillery Regiment. The 75th NVA Artillery Regiment moved from the Ben Cat area to support the 7th NVA Division east of Route 13.
The 5th ARVN Division made no determined effort during July or August to alter the status quo. The NVA, however, pulled the 95C Regiment out of Base 82 and replaced it with the 141st Regiment of the 7th NVA Division, in time to meet the next concerted ARVN effort to take Base 82.
By autumn the 8th Infantry, 5th ARVN Division, had been selected to try to plant South Vietnam's red and yellow banner on Base 82, having replaced its sister regiment, the 7th, in the Iron Triangle. Prior to an attack scheduled for 7 September, ARVN reconnaissance patrols had successfully reached the base's perimeter. The 8th Regiment formed a task force around its 1st and 2d Battalions, reinforced by the 5th Division Reconnaissance Company and a small armored troop with three M41 tanks, three M-48 tanks, and three armored personnel carriers. The 1st Battalion advanced south of Route 7, while the 2d Battalion, with the reconnaissance company and the armored troops, advanced on an axis north of the road. Unopposed and moving quickly the two battalions reached the outer defenses of Base 82 in the early morning of 7 September but could go no further that day. Faced with barbed wire and mines and under fire from the front and flanks, the 8th Infantry dug in. As the rain of enemy shells continued, much of it heavy 120-mm. Soviet mortars, the 8th kept digging and improving fighting positions with logs overhead.
On 8 September, the NVA shelling increased, and at 1600 it began to rain, ending all VNAF aerial observation and air support for the 8th Infantry. As the rain increased, so did the enemy bombardment, 1600 rounds falling in one hour, and the battlefield was obscured in smoke. ARVN infantry could hear the approach of tanks. One column of T-54's came out of the rubber plantation and forest to the north, and another line of six advanced from the south. The three ARVN M-48's withdrew, and at 1800 hours, nearly caught in a double envelopment, the 8th Infantry fell back, first about 300 meters where the leaders attempted to establish a new line, then 300 meters farther back where the troops of the 8th rallied and held on the western slope of Hill 25.
With victory seemingly so close, General Thuan was deeply disappointed by the rout of the 8th Regiment, and his disappointment changed to anger when he learned of the relatively light casualties suffered by the 8th: 6 killed, 29 missing, and 67 wounded. But even if the 8th Infantry leaders on the scene could have held their troops in their exposed positions in front of Base 82, the regiment probably could not have survived the NVA counterattack. In any case, General Thuan ordered an immediate investigation of the circumstances of the 8th Infantry's failure and subsequently dismissed the regimental commander. On 11 September, the 8th Infantry was replaced in the Iron Triangle by the 9th, and the final phase of the fight to retake Base 82 was about to begin.
All three battalions of the 9th Infantry moved into position on the west slope of Hill 25. Combat losses since the start of the NVA offensive in May, combined with the slow flow of the replacements into the regiment, had reduced battalion strength to under 300. Between 12 and 18 September, the 9th concentrated on reconnaissance, planning, and improvement of positions. As the ARVN 9th Regiment prepared for the attack, the NVA was beginning to execute another relief in the Ben Cat battlefield. The 141st Regiment of the 7th NVA Division made preparations to leave the Base 82 area and turn over its defense once again to the 95C Regiment of the 9th NVA Division.
With the 2d Armored Cavalry Squadron protecting the right (north) flank, and two Ranger battalions protecting the left, the 9th ARVN Infantry Regiment began its attack toward Base 82. The two attacking battalions, the 3d Battalion on the right, north of Route 7, and the 2d on the left, crossed the line of departure on Hill 25 on 19 September. Moving slowly, with excellent reconnaissance and effective artillery support, the ARVN infantrymen methodically eliminated, one by one, the enemy's mutually supporting bunkers that lay in a dense pattern all along the route of advance. Although the NVA infantrymen defended tenaciously and their artillery support was heavy and accurate, they gradually gave ground. On 29 September, the 1st Battalion relieved the weary 3d Battalion, and the relentless attack continued. On 2 October, the 2d Battalion, 46th ARVN Infantry, 25th Division, was committed to reinforce the 2d Battalion of the 9th Infantry. Before midnight on 3 October, as enemy artillery and mortars were still firing heavy barrages, a 12-man assault team from the 1st Battalion, 9th Infantry, attempted to breach the barbed wire and scale the earthen wall. An antipersonnel mine detonated, disclosing the team's position, and heavy fire from the base pinned it down. Very early the next morning, the NVA infantry counterattacked, forcing the withdrawal of the assault team. But it became apparent to the ARVN commander on the ground that victory was within grasp. A 100-round concentration of 155-mm. howitzer fire, which he requested, had the desired effect: enemy resistance and return fire was notably diminished by 1300, and a half hour later NVA infantrymen were seen climbing out of their crumbling fortress and running to the rear. At 1500 on 4 October the 1st Battalion, 9th Regiment, raised South Vietnam's flag over Base 82, ending a bitter four-month struggle and the third phase of the Iron Triangle campaign.
Return to Rach Bap
Calm returned to the Iron Triangle as the remnants of the 95C and 272d NVA Regiments withdrew from Base 82. For three days, even the NVA artillery was silent. Meanwhile, far to the north of the Ben Cat battleground and in the COSVN rear area, a significant event was taking place. Recognizing the need to plan and coordinate the operations of multi-divisional forces, COSVN organized a corps headquarters in the Tay Ninh-Binh Long region and designated it the 301st Corps. This corps would soon direct the combat operations of the 7th and 9th NVA Divisions, separate regiments, and additional formations already en route from North Vietnam.
After the long and costly victory at Base 82, General Thuan decided to rest the tired troops of the 5th ARVN Division and turned his attention to sending his 25th Division to clear out the enemy bases in the Ho Bo area west of the Iron Triangle. The ARVN defenses around An Dien and Base 82 were taken over by Regional Forces and Rangers. For what became the fourth phase of the campaign, III Corps Headquarters worked on plans to resume the attack to retake Rach Bap, the last of the three outposts still remaining in enemy hands. General Thuan also recognized the need to clean the enemy out of the southern part of the Iron Triangle, around Phu Thu, and a plan encompassing Rach Bap, Phu Thu, and the Phu Hoa area west of the Iron Triangle began to take shape. But on 30 October, before the execution of the plan, President Thieu relieved General Thuan of command of Military Region 3 and III Corps and replaced him with Lt. Gen. Du Quoc Dong. Other important command changes took place on the same day. The II Corps Commander, Lt. Gen. Nguyen Van Toan, was replaced by Maj. Gen. Pham Van Phu, and Maj. Gen. Nguyen Khoa Nam became the new commander of IV Corps, in place of Lt. Gen. Nguyen Vinh Nghi. Only I Corps was untouched, where Lt. Gen. Ngo Quang Truong retained command.
General Dong immediately surveyed the situation in the Iron Triangle and reviewed the plan of his predecessor, which as modified became operation Quyet Thang 18/24 (Operation Will to Victory). Battalions from all three divisions of the corps were committed; D-Day was 14 November. The 9th Infantry of the 5th ARVN Division, the victors of Base 82, started from An Dien and marched west, along Route 7, past Base 82 toward Rach Bap. The 48th and 52d Regiments of the 18th Division crossed the Thi Thinh River south of Ben Cat and entered the Iron Triangle and attacked west toward the Saigon River. Elements of the 50th ARVN Infantry, 25th Division, were already in this area. Meanwhile, the 46th ARVN Infantry and one battalion of the 50th moved into the plantations north of Phu Hoa District Town to prevent enemy infiltration across the Saigon River.
Along Route 7, the 9th ARVN Infantry advanced without incident until 19 November when sharp fighting west of Base 82 resulted in over 40 ARVN soldiers wounded. The enemy withdrew leaving 14 dead and many weapons and radios behind. The next morning, Reconnaissance Company, 9th Infantry, entered Rach Bap unopposed. The Iron Triangle campaign was virtually over, although mopping_up operations continued in the south along Route 14 until 24 November. Measured against the costs and violence of the earlier phases of the campaign, this final chapter was anticlimactic. Casualties on both sides were light, and contacts were few and of short duration. The NVA had given up its last foothold in the Iron Triangle with only token resistance in order to replace losses, reorganize, re-equip, and retrain the main forces of the new 301st Corps for the decisive battles to come.
As mentioned earlier, the NVA 16 May offensive in Binh Duong Province was a two-division attack, with the 9th NVA Division west of Route 13 into the Iron Triangle and the 7th NVA Division east, against Phu Giao District. The principal 7th Division objective was the bridge on Interprovincial Route 1A (LTL-1A) over the Song Be south of the major ARVN 5th Division base at Phuoc Vinh and northeast of the Ben Cat-Iron Triangle battlefield.
The 7th NVA Division on 5 April overran the ARVN outpost at Chi Linh. After taking Chi Linh, the division's 141st Infantry Regiment remained in the Chon Thanh area until detached for duty in the Iron Triangle under the 9th NVA Division. Meanwhile, the other two 7th Division regiments were preparing for the May offensive in the jungles around Phu Giao. The 165th NVA Infantry Regiment was west of Route 1A and north of the Song Be; the 209th NVA Infantry Regiment was south of the Song Be, with battalions disposed on both sides of Route 1A. But sometime before 16 May, the 165th crossed the Song Be and moved into attack positions in the Bo La area, south of Phu Giao, and the 209th moved north to positions close to the Song Be bridge. The 7th NVA Division's plan called for the 165th to attack ARVN positions and block Route 1A south of the bridge, while the 209th would seize the bridge and its controlling terrain.
The defense of the Song Be bridge was the responsibility of the 322d RF Battalion, while the 7th and 8th Regiments of the ARVN 5th Division and the 318th Task Force were in position to provide support from the Phuoc Vinh base south to the Bo La area. Based on good intelligence, the 8th ARVN Infantry attacked assembly areas occupied by elements of the 209th NVA Infantry on 15 May. The disruption caused by this attack was probably largely responsible for the poor showing made by two battalions of the 209th which, the following morning, attacked RF outposts around the Song Be bridge. In any event, the troops of the 322d RF Battalion fought off the attack, losing a few positions but maintaining control of the key terrain and the bridge.
Meanwhile, the 165th NVA Infantry Regiment had better success in attacking the Bo La area, managing to hold enough of Route 1A to prevent reinforcements from breaking through to the bridge. But its accomplishment was short-lived. The 5th ARVN Division reacted immediately and sent its 7th Infantry Regiment and the 315th Task Force north to break the block on Route 1A. Casualties on the ARVN side were light, but the NVA lost heavily; the 209th was especially hard hit by ARVN artillery and air strikes in the bridge area. By 23 May, despite reinforcement of the 165th NVA Regiment by a battalion of its sister regiment, the 141st, the ARVN tank and infantry counterattack had cleared the road to the bridge and beyond to Phuoc Vinh. Although the 7th NVA Division maintained its 165th and 209th Regiments in the Phu Giao area for the rest of the summer, the strategic raids campaign in eastern Binh Duong Province was a failure, essentially over a week after it began, and the ARVN successfully countered the sporadic attacks the enemy continued to make along Route 1A in the Phu Giao area.
Colonel William E. Le Gro