How US Airstrikes Defeated North Vietnam in the 1972 Battle of An Loc

In the early morning hours of March 30, 1972, a massive barrage from four North Vietnamese Army artillery regiments slammed into the newly formed 3rd Infantry Division of the Army of the Republic of Vietnam in South Vietnam’s northernmost province. Under cover of these fires, two NVA divisions poured across the Demilitarized Zone toward the town of Quang Tri. At the same time, another NVA division attacked from the west toward Hue, Vietnam’s ancient imperial capital.

The March 30 attack was the opening of North Vietnam’s Nguyen Hue Campaign (named for an emperor in the 1700s who united the northern and southern parts of what became Vietnam), also commonly known as the Spring Offensive of 1972 or the Easter Offensive.

The offensive consisted of a three-front attack that hit towns in the north, central and southern regions of South Vietnam in an effort to strike a knockout blow against the South Vietnamese government and ARVN.

A total of 14 NVA divisions and 26 separate regiments, totaling 125,000 troops and approximately 1,200 tanks and other armored vehicles, participated in the offensive. The North Vietnamese also introduced weaponry not used in earlier Communist offensives in South Vietnam, such as T-54 tanks, ZSU 57-2 tracked anti-aircraft guns and SA-7 Strela shoulder-fired, heat-seeking anti-aircraft missiles. The NVA’s combined arms assaults—featuring coordinated masses of infantry, tanks and artillery—were more like the Red Army’s attacks in the latter stages of World War II than the previous battles in Vietnam.

Indeed, U.S. Army Capt. Harold Moffett, an adviser working with South Vietnam’s 3rd Ranger Group, described the scene in the especially hard-hit southern city of An Loc as “looking like Berlin at the end of World War II.”

According to captured documents and NVA sources, the North Vietnamese hoped to destroy much of the ARVN and occupy key cities, which would put the Communist forces in a posture to threaten Saigon and President Nguyen Van Thieu’s government.

Soon after the initial thrust in South Vietnam’s northern region, another NVA force attacked Kontum in the Central Highlands with three divisions. On April 4, the NVA opened the offensive on this front with a massive artillery and rocket barrage of ARVN firebases along Rocket Ridge, northwest of Kontum City.

North Vietnam Targets An Loc

Meanwhile, to the south three more NVA divisions advanced in the Saigon region, focusing on Binh Long province, north of Saigon and bordering Cambodia. One of the primary targets was the provincial capital, An Loc, a city of 15,000 surrounded by vast rubber plantations totaling 75,000 acres.

Only 65 miles north of Saigon, An Loc was in a dangerous spot astride Highway 13, a paved road that could take Communist forces directly from the Cambodian border to the South Vietnamese capital.

The coordinated Communist thrusts, characterized by a ferocity never before experienced by South Vietnam’s forces, were initially successful. In some of the most bitter fighting of the war, the South Vietnamese defenders reeled under the NVA assaults.

By this time in the war, most U.S. ground combat forces had been withdrawn, and Americans on the ground in combat roles were primarily advisers who served with ARVN forces in the field. President Richard Nixon had instituted in 1969 his “Vietnamization” program: a gradual transfer of combat operations to the South Vietnamese so that all American troops could be eventually withdrawn. To achieve that goal, the U.S. had to strengthen the South Vietnamese army and bolster Thieu’s government until they could stand on their own against North Vietnam’s Communists.

In one of the critical aspects of the Vietnamization program, Military Assistance Command, Vietnam, or MACV, the senior U.S. military headquarters in-country, increased the number of advisers to help improve the quality of the ARVN force. U.S. advisers had been serving with South Vietnamese units since 1955, but they took on added importance as the number of American combat units dwindled.

There were U.S. advisers at corps, division and regimental levels. The elite airborne, ranger and marine units also had American advisers with each battalion. Other advisers were assigned to each South Vietnamese province and district headquarters. These advisers would figure prominently in the ARVN defense against the North Vietnamese invasion in spring 1972.

On April 2, the offensive in the Saigon region began when the 24th and 271st NVA regiments attacked 25th ARVN Division firebases along the border with Cambodia in Tay Ninh province, which abuts Binh Long’s western boundary. The Tay Ninh attack, supported by tanks, rockets and heavy mortar fire, seemed to confirm earlier intelligence that the main North Vietnamese effort in the region would take place in that province, although the South Vietnamese were surprised at the fierceness of the attacks and the use of tanks.

For three days after the Tay Ninh attacks, Binh Long was relatively quiet. The only ARVN division in the province was the 5th Infantry Division, commanded by Brig. Gen. Le Van Hung.

Senior U.S. advisers with the division picked up indications of increased enemy activity in the area, but MACV analysts in Saigon insisted that the main attack would come in Tay Ninh. The analysts would soon be proved wrong.

About 6:50 a.m. on April 5, the enemy arrived in Binh Long province with a coordinated attack on Loc Ninh, a town on Highway 13 about halfway between An Loc and the Cambodian border. The North Vietnamese attackers relentlessly employed tanks and large volumes of artillery, mortar and rocket fire against the small ARVN force of about 2,000 troops (mostly from the 9th Regiment of the 5th ARVN Division and the local militia garrison) and their seven American advisers.

Lt. Gen. Nguyen Van Minh, commander of the military region surrounding Saigon, and Maj. Gen. James F. Hollingsworth, his American adviser, at the region’s headquarters in Bien Hoa just outside Saigon, realized that Binh Long, not Tay Ninh, was the focus of the main attack and directed all available tactical air support to assist the beleaguered garrison. Skillful coordination of this air support by the American advisers in Loc Ninh inflicted heavy casualties on the attackers, but ultimately the sheer numbers of the North Vietnamese troops overwhelmed the defenders. The ARVN positions fell in late afternoon on April 7. While some ARVN soldiers and one of the advisers escaped, the others were killed or captured.

As the battle unfolded in Loc Ninh, the NVA also attacked an 18th ARVN Division regimental-size task force, designated TF-52, under the operational control of the 5th ARVN Division commander. The task force had been conducting operations from two small firebases west of Highway 13 between Loc Ninh and An Loc. The NVA overran the ARVN positions and forced the task force’s survivors to withdraw into An Loc. During that process, the three advisers with the task force were wounded and evacuated.

The North Vietnamese planned to hit An Loc with three Viet Cong divisions and supporting forces. By this stage of the war, although some Communist formations still carried the traditional Viet Cong designations, the three divisions were organized and equipped as main-force NVA units manned primarily by North Vietnamese soldiers who had come down the Ho Chi Minh Trail. These divisions ranged from 7,000 to 9,000 soldiers. An additional 10,000 NVA troops in various support units would also participate in the battle for An Loc.

The 9th VC Division, considered one of the elite NVA divisions, was sent against An Loc itself, while the 7th NVA Division was ordered to cut Highway 13 between Chon Thanh and Lai Khe to stop supplies and reinforcements moving north from Saigon. And the 5th VC Division, which had initiated the Binh Long campaign at Loc Ninh, was to join the 9th VC Division in its assault on An Loc after securing Loc Ninh.

The Siege Begins

Shortly after the fall of Loc Ninh, the 9th VC Division made its opening move against An Loc by seizing the airstrip at Quan Loi, just 2 miles northeast of the city. Meanwhile, south of the city, the 1st ARVN Airborne Brigade, which had been shifted from Saigon to Binh Long, was directed to move up from Lai Khe to reinforce the An Loc garrison. The airborne forces, traveling north on Highway 13, immediately ran into heavy contact with elements of the 7th NVA Division, by then entrenched in blocking positions across the highway.

With the loss of the Quan Loi airstrip and the imposition of roadblocks on Highway 13, An Loc was surrounded and cut off from the outside, a siege that would last for more than two months.

A brief lull occurred as the NVA prepared for the main attack on the city itself. By the afternoon of April 12, ARVN forces in and immediately around An Loc had grown to nine infantry battalions, consisting of regular infantrymen from elements of the 5th and 18th divisions, rangers and local militia forces. General Hung, the 5th ARVN Division commander, was given operational control of all South Vietnamese units in the city, about 3,500 soldiers—grossly outnumbered by the NVA forces surrounding An Loc.

Preparations for a direct assault on An Loc began in the early morning of April 13, when the North Vietnamese brought a wide range of guns, rockets and mortars to bear on the city. Shortly after dawn, the NVA forces began a coordinated tank and infantry attack from the northeast. Soviet-made T-54 and PT-76 tanks stormed down the main north-south street into An Loc.

Many of the ARVN defenders had never encountered tanks before and panicked. Several units broke and ran. The situation stabilized somewhat when an ARVN soldier knocked out one of the lead tanks with an M72 light anti-tank weapon, confirming that ARVN infantrymen could stop tanks.

The battle raged for three days as the NVA advanced house-to-house. Casualties were heavy on both sides. The NVA had lost 23 tanks but had forced ARVN defenders in the southern part of the city into a small redoubt, measuring just 1,000-by-1,600 yards.

The NVA held the northern part of the city; in many cases the opposing forces there were separated only by the width of a city street.

Meanwhile, other NVA forces completely surrounded the city. The battle seesawed back and forth.

On several occasions, the attackers almost succeeded in taking Hung’s command bunker.

Communist forces lose momentum

After three days, the intensity of the fighting abated somewhat as the North Vietnamese momentum was slowed by continual pounding from the air. U.S. advisers coordinated airstrikes with ARVN units engaging the NVA on the ground. Air Force, Navy and Marine attack aircraft, AC-130 gunships and Army Cobra attack helicopters hit the NVA inside An Loc, while General Hollingsworth directed B-52 bomber strikes against North Vietnamese staging areas in the rubber plantations around the city. This air support saved the ARVN from almost certain defeat and set the pattern for U.S. and South Vietnamese actions during the next two months.

Even though the airstrikes hampered NVA movement, the Communist forces were still able to tighten their stranglehold on An Loc while shelling the city heavily. They had hit An Loc with 25,000 artillery rounds and rockets during the first three days of the attack and continued to fire 1,200 to 2,000 rounds per day into the city for the next week as they regrouped for a renewed assault.

On April 16, General Minh directed the 1st Airborne Brigade to send troops by helicopter to the high ground southeast of An Loc to reinforce the city. That same day he received operational control of the 21st ARVN Division, which had been in the Mekong Delta, and ordered the division to Lai Khe for an attack up Highway 13 to relieve An Loc.

NVA commanders, who had hoped to occupy An Loc no later than April 20, revised the attack plan and repositioned their forces for an assault from the east.

The 9th VC Division would make the main attack against the city, while elements of the 5th VC and 7th NVA divisions attacked the 1st Airborne Brigade positions southeast of An Loc. To counter American air support, the NVA moved up additional anti-aircraft weapons, including Soviet-made, shoulder-fired Strelas.

The second major attempt to take An Loc began in the pre-dawn hours of April 19 with a massive artillery bombardment of both the city and the 1st Airborne Brigade positions. The North Vietnamese overran one airborne battalion and drove the two other battalions out of their positions and into the city.

Inside the city, the ARVN defenders and their advisers fought off repeated waves of attacking NVA troops supported by tanks and finally beat them back with the help of unrelenting air support.

A “Ghastly” Human Toll

The North Vietnamese attacks had abated somewhat by April 20. However, conditions inside the city continued to deteriorate drastically. The NVA was still pouring a withering amount of tank, rocket, mortar and artillery fire into the city. The South Vietnamese soldiers lived underground with the unfortunate civilians who had been unable to leave before the NVA attacked. Moving around above ground invited near-certain death.

Most of An Loc’s buildings had been destroyed in the repeated ground attacks, shelling and airstrikes. The city was strewn with mounds of rubble, shattered trees, garbage and dead domestic animals. The human toll was ghastly.

Captain Moffett, the adviser to the 3rd Ranger Group, reported that “the bodies of men, women and children are everywhere.”

A South Vietnamese soldier later remembered the agonizing screams of the wounded and dying and “the bodies and body parts blown around the area, even hanging from tree limbs or laying on the roofs of houses.” The smell of death permeated the air.

Innumerable diseases, including cholera, soon ran rampant. To avoid a full-fledged epidemic, bodies were buried in mass graves by soldiers operating bulldozers during the infrequent lulls in the shelling. Some graves contained 300 to 500 corpses, and many bodies had to be reburied after exploding shells churned up the original graves.

There was so much anti-aircraft fire that it became almost impossible to resupply An Loc’s defenders by air. Medical supplies were exhausted. The food and ammunition situation was not much better. Little could be done for the increasing number of casualties. There was no way out for the wounded.

ARVN resolve and morale plummeted. U.S. advisers were afraid the South Vietnamese troops would break if the NVA attacked in force. The Americans redoubled their efforts to bolster the confidence of their ARVN counterparts. Under these bleak conditions, the defenders, now numbering about 4,500 troops with the arrival of the two airborne battalions, prepared for the next North Vietnamese onslaught.

Having been stopped twice, the NVA again changed its plans. The 9th VC Division commander was reprimanded for failing to accomplish his mission after two attempts, and the new mission was given to the 5th VC Division commander. The plan called for the 5th to make the main attack, supported by elements of the 7th NVA and 9th VC divisions.

The attack began at 5 a.m. on May 11 with an opening artillery barrage. During the next 12 hours, An Loc was struck by 10,000 rounds of artillery fire. Under this bombardment cover, the NVA attacked with seven regiments from the north and northwest. The attacks, supported by tanks, were successful in forging two salients in the ARVN lines, almost bisecting the defensive perimeter. The fighting was intense, and the city’s defenders were close to the breaking point on several occasions.

U.S. Airstrikes turn the Tide

Continuous air support, however, prevented a disaster. The airspace over An Loc was crowded as U.S. Air Force, Navy and Marine close-support aircraft, AC-130 gunships, Cobra attack helicopters and B-52s vied for position to pummel the attackers. Advisers on the ground worked with airborne strike coordinators to make maximum use of the available aircraft. During the battle, 297 sorties were flown on May 11, followed by more than 250 on each of the next four days. Additionally, 30 B-52 missions on May 11 struck enemy positions surrounding An Loc.

This air support, flown in the face of some of the most severe anti-aircraft fire ever encountered in South Vietnam, broke the NVA attack, enabling the ARVN forces to stabilize their lines and eventually push back the enemy.

Unfortunately for the An Loc relief effort, the battle along Highway 13 was not going as well. The 21st ARVN Division had fought its way up the road almost inch by inch, sustaining heavy casualties. But the ARVN attacks were not coordinated and failed to dislodge the entrenched North Vietnamese forces along the road. Although the 21st Division wasn’t able to link up with the An Loc forces, it had tied down most of one NVA division, which thus was unavailable for the battle in the city. That was a major contribution by the South Vietnamese unit because one more NVA division in the direct assault on An Loc would almost certainly have tipped the scales in the attackers’ favor.

By the end of May, although the fighting was not over, the tide had turned in favor of the defenders. Around-the-clock airstrikes took a horrendous toll on the NVA forces. ARVN intelligence estimated that the Communist forces sustained 10,000 casualties in An Loc during April and May. In early June, General Minh was able to get reinforcements into An Loc and withdraw the much battered 5th ARVN Division. On June 18, Thieu declared the siege of An Loc broken.

Even then, enemy artillery and mortar rounds continued to fall on An Loc. The shelling, estimated at more than 78,000 rounds during the two-month period, had reduced the city almost to ruins. The ARVN defenders had sustained 5,400 casualties, including 2,300 dead or missing. Many of the advisers had been wounded at least once. As Maj. John Howard, an adviser with the 1st Airborne Brigade, described it: “The graves, burned out vehicles, and the rubble were mute testimony to the intensity of the battle that had been fought there.”

Despite the costs, the defenders and their advisers, with the help of American air power, had decisively defeated three of the NVA’s finest divisions and held An Loc against overwhelming odds.

The NVA attacks in the central and northern regions of South Vietnam were eventually thwarted as well. In late May, the ARVN defenders at Kontum, supported by massive U.S. airstrikes and missile-equipped anti-tank helicopters, rebuffed the NVA attacks. Quang Tri, captured by the Communists in late April, was retaken in September with assistance from U.S. air power and naval gunfire from ships in the South China Sea.

South Vietnamese morale was high, and Nixon proclaimed “Vietnamization” a resounding success. After a peace agreement in January 1973, the last American troops departed that March. But fighting resumed in Vietnam after a brief cease-fire, and reduced U.S. aid had an impact on South Vietnam’s combat capabilities.

When the North Vietnamese launched an offensive in early 1975, South Vietnamese forces, without the U.S. advisers and air support that had been crucial in 1972, were defeated in 55 days. The valor and sacrifice of spring 1972 had been in vain. 

James H. Willbanks, a retired Army lieutenant colonel, was an adviser with a South Vietnamese regiment at
the Battle of An Loc.  He was wounded at An Loc on July 9, 1972. He is the General of the Army George C. Marshall Chair of Military History at the Army’s Command and General Staff College at Fort Leavenworth, Kansas, and the author or editor of 14 books including The Battle of An Loc (Indiana University Press, 2005).

This article was published in the August 2017 issue of Vietnam magazine.