South Vietnam's ground war, 1972-1975

See also: Vietnamization

See also: Fall of South Vietnam

See also: U.S. foreign military assistance organizations

After the full implementation of the Vietnamization doctrine, the U.S. saw the Army of the Republic of Viet Nam (ARVN) as taking responsibility for ground combat in South Vietnam between 1972 and 1975, with both direct air and naval combat support from U.S. forces, as well as combat support in areas such as intelligence and communications, and combat service support in supply and maintenance. This article excludes the final North Vietnamese offensive and fall of South Vietnam.

In the face of declining U.S. popular support of the war, the Nixon Administration had adopted the Vietnamization doctrine, in which U.S. ground troops would no longer fight in South Vietnam, although, subject to negotiations with the Communists, there would be U.S. foreign military assistance to the South, and always the threat of U.S. air and naval attacks against the North. While the North Vietnamese would not directly fight U.S. ground troops, the potential of their return, or of much greater support to the South Vietnamese, would be an incentive to serious negotations, assisted by other Communist powers that also believed an end to the confrontation was in order.

Nixon's larger strategy was to convince Moscow and Bejing they could curry American favor by reducing or ending their military support of Hanoi. He assumed that would drastically reduce Hanoi's threat. Second, "Vietnamization" would replace attrition. Vietnamization meant heavily arming the ARVN and turning all military operations over to it; all American troops would go home.

U.S. intelligence and policymakers, however, did not accept that the North Vietnamese took a long-term view, and, in hindsight, never rejected their intention to conquer the south. They did, however, abandon their General Offensive-General Uprising doctrine. Their need to fight units of full U.S. capability became moot, because even Vietnamized troops would not have the combat power of American troops. Further, South Vietnamese politics, as well as the long experience needed to qualify a thoroughly capable general, would create a disparity of with the North Vietnamese, who retained and encouraged competent commanders.

The North Vietnamese continued to target American opinion, to reduce support to the South and make a serious reinforcement politically acceptable.

By 1972, the North Vietnamese committed to a conventional invasion against the South. While it was repelled, the eventual Paris treaty further restricted U.S. involvement, and the endgame came with a new conventional invasion that led to the fall of south Vietnam in 1975. It defeated the South Vietnamese government, but also ended a war of decades.

Cambodia: a first sanctuary breached

North Vietnam, for different reasons, had always used sanctuaries in Cambodia and Laos. Operating from Cambodia, their troops had a short exposure to being attacked while moving against Saigon and the Mekong Delta. They also had some major command centers not far into Cambodia.

Nixon, with Creighton Abrams' approval, believed that major ground offensives into Cambodia, by combined U.S. and South Vietnamese forces, would change the balance of power and improve the South Vietnamese chances. There had been an unacknowledged bombing program that ws not decisive. In April, two major but mutually supporting operations took place, one into the Parrot's Beak area and the other the Dragon's Jaw.

The Parrot's Beak, according to Nixon's speech on April 30, contained major command facilities. It is the part the Cambodian province of Svay Rieng that juts into the southern Vietnamese provinces of Tay Ninh and Long An provinces. It was the site of a U.S. operation against North Vietnamese sanctuaries in 1970, and a North Vietnamese operation against the Khmer Rouge in 1978.

• Gen. Cao Van Vien, Leadership. McLean, VA: General Research Corporation [on a contract with the U.S. Army], 1978. v, 201 pp. General Vien had been Chairman of the Joint General Staff, Republic of Vietnam Armed Forces. [1]

1972

1972 was to mark a basic change in North Vietnamese tactics, when they switched from guerilla and hit-and-run raids to conventional combined arms combat.

While the Politburo of North Vietnam changed their military methods radically from those of the Tet Offensive, they still hoped for their military success to trigger a popular uprising.new draft laws produced over one million well-armed regular soldiers, and another four million in part-time, lightly armed self-defense militia.

Easter invasion

North Vietnam began preparing the battlefield for its major invasionm which they called Operation Nguyen Hue and the non-Communist side called the Easter (or Eastertide) Offensive, involved three separate corps-level attacks by 12 divisions. They built an air defense network to protect what was to be their rear areas, north of the DMZ. This included S-75 Dvina (NATO reporting name SA-2 GUIDELINE) surface-to-air missiles that shot down three U.S. fighter-bombers in February.

The main attack came with the start of the monsoon season, which prevented close air support and even good artillery fire control. When artillery was available, however, the PAVN 130mm guns had greater range than ARVN howitzers, and could be countered only by tactical aircraft.

In March, 1972 Hanoi invaded on three fronts:

• Northern provinces with a six-division force
• Central highlands, driving for the coast, using three divisions
• Saigon area, employing three divisions

Operations in the North (RVN I Corps area)

I Corps tactical zone, at the start of the invasion, was under the command of a Thieu loyalist, Hoang Xuan Lam, who had commanded the failed 1971 Operation Lam Son 719. I Corps had three infantry divisions, of which the 1st and 2nd were experienced. It also had a separate infantry regiment, a Ranger Group of 3 regular and 6 border defense battalions, an armored brigade, Marines and Airborne in reduced division strength, 6 Regional Force battalions, and corps engineers and artillery.

The northern operation, launched on March 31, used three divisions for the attack, followed later by another three divisions. It was under the direct control of the national command in Hanoi, and was timed for the beginning of the monsoon season, which would limit air support. The PAVN 308th, 304th Divisions moved into Quang Tri province, followed by the 324B division attacking ARVN positions west of Hue.

Receiving the brunt of the attack, however, was the newly formed 3rd ARVN Division, under BG Vu Van Giai, reinforced with the 147th Marine Brigade, 1st Airborne Brigade (detached from the Airborne Division), and 5th Armored Brigade. This was an odd mixture of troops for a critical area; the 3rd Division had only one regiment of experienced soldiers, while its other two regiments were made up of troops "who had been sent to the northernmost province of SVN as a punishment." Truong, however, said that the battalions of the 3rd were experience, but the division and two of the regimental headquarters were new. Further, it was still receiving communications equipment and artillery, and it was not ready to fight a large conventional action.

3rd Division retreat

While the RVN Marines and Airborne had excellent reputations, they were not used in the best possible way. Given their skill, assigning them to a fixed defense line prevented their use as a mobile reserve. An army may place low-quality troops on a border, to pin the enemy while more powerful and mobile units maneuver for a counterattack, but, in fairness, the ARVN simply may not have had enough soldiers to cover the area and leave adequate reserves.

Further complicating matters, while the Rangers were attached to the 3rd Division, their own group headquarters stayed in Danang, under COL Trang Cong Lieu; the Rangers would often not comply with orders from BG Giai until they had confirmed them with COL Lieu. In like manner, the Marine Division headquarters was in Hue, but not subordinate to the I Corps commanding general. Again, when BG Giai issued an order, it might not be followed by the Marines until they confirmed it with their headquarters. BG Giai eventually had theoretical control of 9 brigades with a total of 23 battalions, supervision of province and district level forces, and corps artillery and logistics within his operational area. Even if he had all the communications equipment that would normally be assigned to a division, and he did not, and there were no conflicting order from other headquarters, this was far too many unit for him to control. The traditional military rule of thumb is a commander can reasonably control 3 to 5 maneuver units, plus supporting troops.

MG Lam, the corps commander, did not assist BG Giai, but focused on planing a counteroffensive. First, he thought of moving north, but eventually changed to counterattacking west, with the 3rd division as the heart of the attack, to go in on April 14. Not only did confusing orders go to his Marines and Rangers, MG Lam would also give direct orders down to battalion level.

These forces fell back, first to Dong Ha. They then linked to a defense line manned by the rest of the Airborne Division and another Marine brigade, south of the My Chanh River. There was a disorderly retreat, compounded by bad weather limiting the use of air support. Throughout April, the PAVN continued to press toward Quang Tri, which was abandoned on May 1.

While the 3rd division broke completely, the Marines held, and, with a new corps commander, BG Ngo Quang Truong replacing Gen. Lam, reorganized and counterattacked from the Hue area. When Hue held, the PAVN fell back, and came under B-52 attack. During this time, Operation LINEBACKER I was becoming increasingly effective in interdicting the PAVN supply lines.

Given maneuvering room, Truong's rebuilt force of Airborne and Marine divisions came together to attack Quang Tri of May 29. They also launched an assault to retake Hue.It was not a short campaign, but they retook Quang Tri on September 15, which gave Henry Kissinger negotiating leverage in the Paris Peace Talks.

Operations in Central Vietnam (RVN II Corps)

Under the control of PAVN Military Region V, attacks began on April 23, with the NVA 3rd Division feinting at Binh Dinh, while the 2nd and 10th Divisions attacked Kontum, originally held by the ARVN 22nd division, which, over the protests of its armored component commander, used tanks as fixed defenses. The division operations center at Tan Canh was overrun, as was a strongpoint at Dak To. The PAVN consolidated, including making use of captured artillery, between 25 April and 9 May, attacking Polei Kleng and Ben Het Ranger camps along their supply line. While Polei Kleng fell on May 9th, Ben Het held.

Both sides introduced new technology On the 9th, Ben Het had been assisted by a new weapons, helicopters firing the early XM26 model TOW antitank missile. During their attack, the PAVN had used ground-fired antitank missiles, the Soviet 9M14M Malutka/NATO designation AT-3 SAGGER.

The ARVN 23rd division, making especially good use of its tanks, threw back the attack at Kontum. Its commander, BG Ly Tong Ba, had commanded South Vietnam's first mechanized infantry company, in 1962, using M113 armored personnel carriers at the Battle of Ap Bac; his experience served him well. As well as using his armor, he trained his infantry in the use of the M72 light antitank weapon.

Operations in the Saigon arrea (RVN III Corps)

Beginning on April 2, the composite PAVN/VC 5th Division attacked the firebase at Lac Long in Tay Ninh province, secured a position there, and moved against their main targets at Loc Ninh, Quan Loi and An Loc. These towns, with airfields, were positioned along Highway 13 to Saigon. The Communists intended to hold ground and create a regional government that could be represented in future negotiations.

Before the attack, ARVN forces in An Loc consisted of elements of the 9th division, the 3rd Ranger Group, and provincial troops. Reinforcements fro the 1st Airborne Brigade and 81st Airborne Ranger Brigade were airlifted to a landing zone 3km southeast of An Loc, and had to fight their way into the city. Still, the total defense was 6,350 men under BG Le Van Hung. It should be noted that except for Marines, elements of every part of the ARVN strategic reserve was part of the defense. President Nguyen Van Thieu called An Loc, under 24 hour shellfire, the symbol of South Vietnamese resistance, and sent in his palace guards as reinforcements.

While the first attack, starting with a strong artillery preparation, pushed the 8th Regiment of the 5th Division, and the 3rd Ranger Group, from a hill and the airstrip. U.S. AC-130 gunship support stopped the infantry advance. As was the ARVN, the PAVN was still inexperienced in combined arms operations, a basic rule of which is that tanks always operate with infantry; the two branches complement one another. PAVN tanks, however, pushed on by themselves, and seven were destroyed in the attack, some by young Self-Defense force soldiers.

The next attack came on the 15th, and, again, they sacrificed tanks sent in without infantry. A B-52 strike hit the regimental headquarters, and the attack was called off.

May 11 was the day of the most intense assault, with one PAVN division striking from the northeast and another from the southwest, both with artillery preparation. By nightfall, the situation was in doubt; NVA forces came within a few hundred meters of the division command post. On the next day, while the PAVN tried to penetrate, they were pushed back by the garrison, assisted with close air support.

During the battles, there had been continuing suppression of enemy air defense, and, by early June, helicopters could survive to land in An Loc. On June 19, the ARVN 21st division, reinforced with another infantry regiment, and the 9th Armored Cavalry Regiment, broke through on Highway 13.

Unquestionably, U.S. airpower, including B-52s and close air support by AC-130s and fighter-bombers, played a key part. Thieu worried even more about his ability to resist without that support. Nevertheless, the ARVN ground forces fought hard. GEN Abrams summarized

I doubt the fabric of this thing could have held together without U.S. air, but the thing that had to happen before that was the Vietnamese, some numbers of them, had to stand and fight. If they do not do that, ten times the air we've got wouldn't have stopped them.

Stabilization and Provisional Governernment

Improvements in the weather allowed the U.S. to interdict the PAVN supply lines, and their offensive slowed; they moved back to secure an area south of the DMZ. This area was proclaimed under the control of the "Provisional Revolutionary Government of South Vietnam" (PRG). it welcomed diplomats from the Communist world, including Fidel Castro, and served as one of the launch points of the 1975 invasion. The PRG areas now contained five PAVN divisions.

The RVN relaxes

Some ground north of My Chanh was regained by the Airborne Division on the East and Marine Division on the West.

On September 14, the RVN Marines reentered Quang Tri.

After the failed Easter Offensive the Thieu government made a fatal strategic mistake, going to a static defense and not refining its command and control for efficiency, not political reward. Control of military forces remained at the corps level, which a special problem for the Republic of Vietnam Air Force. There was also a lack of planning to operate as a national military, to cope with simultaneous attacks against multiple Corps tactical zones.

There was no central command that could order the Air Force, which was of substantial size, to concentrate on battlefield air interdiction of specific areas on the Ho Chi Minh trail or other critical points. Essentially, the aircraft only provided close air support.

The departure of American forces and American money lowered morale in both military and civilian South Vietnam. Desertions rose as military performance indicators sank, and no longer was the US looking over the shoulder demanding improvement.

On other side, the PAVN had been badly mauled--the difference was that it knew it and it was determined to rebuild. Discarding guerrilla tactics, Giap took three years to rebuild his forces into a strong conventional army. Without constant American bombing it was possible to solve the logistics problem by modernizing the Ho Chi Minh trail with 12,000 more miles of roads, as well as a fuel pipeline along the Trail to bring in gasoline for the next invasion.

1973

As soon as the Paris accords were signed, President Nguyen Van Thieu, according to Hanoi, both said, to an unspecified audience. "the cease-fire does not at all mean the cessation of the war" but also refused to tell his troops about the signing. He had the ARVN launch attacks in various areas claimed by the Provisional Revolutionary Government (PRG).

1974

Both sides regularly violated the cease-fire. A group called the Indochina Resource center, formed by Douglas Pike, said that the U.S. and South Vietnam presented the violations as virtually all on the Communist side. It described much of the problem with the Thieu government, which was unwilling to recognize the PRG as a participant in negotiations.

Tran Van Tra formed a planning headquarters, in the south, in 1974, originally planning an attack in 1976.