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.

Subsequent congressional action banned further U.S. ground intervention outside the boundaries of South Vietnam, so the next major drive, Operation Lam Son 719, would have to be based on ARVN ground forces, U.S. air and artillery support, and U.S. advisory and logistical assistance.

1971

The Vietnamization policy achieved limited rollback of Communist gains inside South Vietnam only, and was primarily aimed at providing the arms, training and funding for the South to fight and win its own war, if it had the courage and commitment to do so. By 1971 the Communists lost control of most, but not all, of the areas they had controlled in the South in 1967. The Communists still controlled many remote jungle and mountain districts, especially areas that protected the Ho Chi Minh Trail.

Lam Son 719

Saigon's effort to strike against one of these strongholds, Operation Lam Son 719, failed in 1971. The SVN forces, with some U.S. air support, were unable to defeat PAVN regulars. While the operation is detailed in a separate sub-article, the key issues were that the ARVN were inexperienced in executing large operations. They underestimated the needed forces, and the senior officers had developed in a context that rewarded loyalty rather than competence. Let there be no doubt that there were individual ARVN commanders that would be credit to any military, but, Thieu, like those RVN leaders before him, was constantly concerned at preventing a military coup. "...promotions were won in Saigon, not in battle. And vital to advancement was the avoidance of risk,even at the price of defeat."

• 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

In March, 1972 Hanoi invaded at three points from north and west with 120,000 PAVN regulars spearheaded by tanks. This was conventional warfare, reminiscent of North Korea's invasion in 1950. They expected the peasants to rise up and overthrow the government; they did not. They expected the South's army to collapse; instead the ARVN fought very well indeed. Saigon had started to exert itself; new draft laws produced over one million well-armed regular soldiers, and another four million in part-time, lightly armed self-defense militia.

Eastertide invasion

North Vietnam began preparing the battlefield for its major invasion, by establishing 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.

Operations in the North (RVN I Corps area)

The northern operation, launched on March 31, used three divisions for the attack, followed later by another three divisions. The PAVN 308th & 304th Divisions moved into Quang Tri province, followed by the 324B division attacking ARVN positions west of Hue.

Facing them was the newly formed 3rd ARVN Division, reinforced with the 147th Marine Brigade, 1st Airbone 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." While the RVN Marines and Airborne had excellent reputations, this did not even comply with the 1975 "light at the top, heavy at the bottom" force dispositions. An army may place low-quality troops on a border, to pin the enemy while more powerful and mobile units maneuver for a counterattack.

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.

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. 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.

PAVN planning

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