The Battle of Lộc Ninh was a major battle of the Vietnam War fought during the Easter Offensive, which took place in Bình Long Province, South Vietnam between 4 and 7 April 1972. Towards the end of 1971, North Vietnamese leaders decided to launch a major offensive against South Vietnam, with the objective of destroying Army of the Republic of Vietnam (ARVN) units and capturing as much territory as possible, in order to strengthen their bargaining position in the Paris Peace Accords. On 30 March 1972, two People's Army of Vietnam (PAVN) divisions smashed through the Vietnamese Demilitarized Zone, marking the commencement of the Easter Offensive. They quickly overwhelmed South Vietnamese units in the I Corps Tactical Zone. With the rapid collapse of South Vietnamese forces in the northern provinces of South Vietnam, PAVN and Viet Cong (VC) forces began preparing for their next offensive, targeting Bình Long Province in the rubber plantation region north of Saigon. On 4 April, the VC 5th Division opened their attack on Lộc Ninh, defended by the ARVN 9th Infantry Regiment. After three days of fighting, the vastly outnumbered ARVN forces, though well supported by American air power, were forced to abandon their positions in Lộc Ninh.

Background In December 1971, following the defeat of South Vietnamese forces during Operation Lam Son 719, North Vietnamese leadership in Hanoi decided to launch a major military offensive against South Vietnam. In what became known as the Easter Offensive, the combined PAVN and VC forces employed combined arms tactics using heavy weapons that were a radical departure from the low-intensity guerrilla warfare of previous years. Although North Vietnam eventually used the equivalent of 14 army divisions, its leaders did not seek to win the war outright. Rather, their objective was to gain as much territory and destroy as many units of the South Vietnamese military as possible, in order to strengthen their bargaining position at the Paris Peace Talks.

The Easter Offensive began on 30 March 1972, when the PAVN 304th and 308th Divisions drove across the Demilitarized Zone and attacked ARVN positions in the I Corps Tactical Zone, which consisted of South Vietnam's northernmost provinces. Caught by surprise, ARVN General Vũ Văn Giai ordered his newly created 3rd Infantry Division to withdraw towards the Cua Viet River, where it could reorganize.

On 2 April, ARVN Colonel Pham Van Dinh surrendered his 56th Infantry Regiment at Camp Carroll, which enabled the PAVN to take the former American fire base without a fight. Quảng Trị City was captured by the PAVN on 28 April, following several counterattacks by ARVN units around Đông Hà.

With the northern provinces of South Vietnam under their control, PAVN forces turned their attention to the Cambodian border region north of Saigon, which formed part of the ARVN III Corps Tactical Zone. During the offensive, the objective of the PAVN/VC in the zone was the capture of An Lộc, capital of Bình Long Province. The VC committed three infantry divisions to the mission (5th, 7th and 9th Divisions). PAVN forces comprised one artillery formation (69th Artillery Command), one armored regiment (203rd Armored Regiment), two independent regiments (205th and 101st Regiment), and one sapper unit (429th Sapper Group). The VC 5th Division was to initiate the offensive by taking Lộc Ninh, while the 9th Division was assigned to An Lộc. The 7th Division was ordered to block National Highway 13 to prevent reinforcements from reaching An Lộc.

Prelude In late December 1971, ARVN intelligence in the III Corps had detected the buildup of PAVN/VC formations across the border in neighbouring Cambodia. Even though it was obvious that preparations for a major offensive were under way, ARVN commanders were unable to predict the PAVN/VC's intentions. In January 1972, the VC 5th Division was reported to have taken up positions in Snuol, a Cambodian city located about west of Lộc Ninh. South Vietnamese intelligence also detected the presence of the VC 7th and 9th Divisions in Dambe and Chup respectively. Between January and May 1971, the ARVN mounted Operation Toan Thang TT02, with the aim of destroying VC main force divisions based in Cambodia, specifically in the Snuol area. But due to the death of General Đỗ Cao Trí, the commander of III Corps, in a helicopter accident, the ARVN were forced to retreat from Snuol without achieving their objective.

In February and March 1972, ARVN units patrolling the border with Cambodia detected increased PAVN/VC activity in the Fishhook area, most notably the presence of the VC 5th Division in an area north of Bình Long Province. On 13 March, an ARVN mechanized task force operating in Cambodia discovered a huge depot that contained large quantities of assault rifles, machine guns, rockets, anti-aircraft guns and ammunition in Base Area 354 (Svay Rieng Province) and Base Area 708 (Kampong Cham Province). On 27 March, a VC deserter from a reconnaissance company of the 7th Division revealed that his unit was surveying a portion of road between Tây Ninh and Bình Long in preparation for its next move. Between 27 March and 1 April, more enemy prisoners and documents were captured by the ARVN, which revealed that the VC 7th and 9th Divisions were coordinating their efforts against an unidentified target.

The movements of PAVN/VC forces near the Cambodian-South Vietnamese border during the first three months of 1972 clearly indicated that a major offensive was in the making. However, the whereabouts of the next thrust was the topic that concerned South Vietnamese and U.S. intelligence officers the most. In previous offensives, the PAVN/VC had used Tây Ninh as an invasion route, as it was surrounded by VC bases in War zone C, the Iron Triangle and the Parrot's Beak, Cambodia. South Vietnamese and U.S. military intelligence reached a consensus that Tây Ninh would be the next target for the Easter Offensive. To reinforce that perception, on 2 April, the VC 24th Independent Regiment overran Fire Support Base Lac Long, defended by elements of the ARVN 49th Infantry Regiment, 5th Infantry Division, about northwest of Tây Ninh.

The attacks on Lac Long and other outposts in Tây Ninh were a diversion designed to cover the main thrust into Bình Long Province. To initiate the campaign in Bình Long, the VC 5th Division (numbering about 9,230 soldiers) was ordered to take Lộc Ninh, Bình Long's northernmost town. The VC were supported by the PAVN 69th Artillery Command (3,830 soldiers) and the 203rd Armored Regiment (800 soldiers). In 1972, Lộc Ninh was a small district town situated on Route 13, home to about 4,000 people, mostly members of the various Montagnard tribes. The task of defending Lộc Ninh was entrusted to the ARVN 9th Infantry Regiment, 5th Infantry Division, commanded by Colonel Nguyễn Công Vinh. It was supported by the 1st Cavalry Squadron, 1st Regional Force Battalion and elements of the 74th Ranger Battalion.

Prior to the battle, the 9th Infantry Regiment had occupied the former U.S. Special Forces compound at the south end of the airfield, which was about west of the district center. The district headquarters was defended by more than 200 Regional Forces soldiers, who operated from a Japanese-built fortified bunker system located north of the airfield. To assist the 9th Infantry Regiment, the U.S. military provided seven advisers. The U.S. advisory team at 9th Regimental Headquarters was led by Lieutenant Colonel Richard R. Schott, who was assisted by Major Albert E. Carlson and Captain Mark A. Smith, and two communication specialists, Sergeant First Class Howard B. Hull and Sergeant Kenneth Wallingford. Additionally, Captain George Wanat and Major Thomas Davidson operated from the north end of the airfield, attached to the district headquarters.

Fall of Lộc Ninh From the beginning of April, there was a sharp increase in VC activity along National Highway 13, which connects Bình Long Province with Saigon. Between 3–4 April, Regional Force units clashed several times with the VC, resulting in more than twenty VC fatalities. Also, the French owner of the Cexso Rubber Plantation in Lộc Ninh reported to the ARVN that the VC had established field telephone lines northwest of the district. However, ARVN Colonel Colonel Nguyễn Công Vinh was reluctant to send reconnaissance patrols to that area. On 4 April, the ARVN 9th Reconnaissance Company operating west of Lộc Ninh was destroyed when it came into contact with elements of the VC main force units. On the same evening, the 3rd Battalion, ARVN 9th Infantry Regiment captured two soldiers during an ambush operation. The prisoners revealed that they were from the 272nd Regiment, 9th Division, and that their unit was moving south to prepare for an assault on An Lộc.

At around 06:50 on 5 April, the VC 5th Division moved across the Cambodian border to stage the main attack on Lộc Ninh. The VC assault opened with a heavy barrage of artillery, rocket and mortar fire targeting the headquarters of the ARVN 9th Infantry Regiment and the Lộc Ninh district compound. The VC simultaneously mounted other attacks throughout the ARVN 5th Infantry Division's areas of operations in Lai Khê and Quản Lợi. There was also indirect fire on ARVN positions in Phước Long Province, mainly targeting Phước Vinh, Sông Bé, and Bo Duc. Following the artillery barrage, VC infantry, supported by about 25 tanks, attacked Lộc Ninh from the west. In the initial assault, they tried to overrun the ARVN regimental compound located at the south end of the airstrip. Despite the ferocity of the onslaught, ARVN soldiers held their ground and fought desperately to hold the enemy at bay; ARVN artillerymen lowered the muzzles of their 105 mm howitzers and fired directly at enemy infantry formations moving through the rubber trees.

Even though the situation was stabilized, the ARVN were forced to retreat into small compounds at the north and south ends of the town. The intensity of the attack on Lộc Ninh revealed the true intentions of the PAVN/VC; ARVN Lieutenant General Nguyễn Văn Minh, commander of the III Corps and his American advisor Major General James F. Hollingsworth realized that Bình Long, not Tây Ninh, would be the focus of the offensive. In order to halt the advance, Minh and Hollingsworth directed all available tactical support aircraft towards Lộc Ninh. Almost immediately, Republic of Vietnam Air Force (RVNAF) F-5 and A-1 fighter-bombers, United States Air Force (USAF) A-37s from the 8th Special Operations Squadron based at Bien Hoa Air Base, attack aircraft from the aircraft carrier , and USAF F-4 and AC-130 aircraft from Thailand began flying over the skies of Lộc Ninh. U.S. and South Vietnamese tactical support aircraft were directed against VC and PAVN formations by American advisers on the ground. As the fighting intensified, Colonel Nguyễn Công Vinh ordered the 1st Cavalry Squadron—commanded by Lieutenant Colonel Nguyen Huu Duong—to withdraw from Fire Support Base Alpha to reinforce Lộc Ninh. However, Duong refused, saying he would surrender his unit to the VC instead. Angered, Captain Mark A. Smith reportedly threatened to destroy the 1st Cavalry Squadron with American air power if the squadron didn't fight. From that point on, Smith virtually controlled the ARVN forces. A few moments later, elements of the ARVN 74th Ranger Battalion and the 3rd Battalion, ARVN 9th Infantry Regiment notified the regimental command post that they had broken out and were fighting their way back towards Lộc Ninh. Meanwhile, the 1st Cavalry Squadron began moving west towards the Cambodian border to engage the VC.