Towards the end of 1967, the 198th Tank Battalion of the People's Army of Vietnam's (PAVN) 202nd Armored Regiment received instructions from the North Vietnamese Ministry of Defense to reinforce the 304th Division as part of the Route 9–Khe Sanh Campaign.

After an arduous journey down the Ho Chi Minh trail in January 1968, the 198th Tank Battalion linked up with the 304th Division for an offensive along Highway 9, which stretched from the Laotian border through to Quảng Trị Province.

On 23 January, the 24th Regiment attacked the small Laotian outpost at Bane Houei Sane, under the control of the Royal Laos Army BV-33 "Elephant" Battalion.

To rescue the American survivors inside the Lang Vei Camp, a counterattack was mounted, but the Laotian soldiers who formed the bulk of the attack formation refused to fight the PAVN.

[7] To prepare for their upcoming mission, the 203rd Armored Regiment undertook a series of combined-arms training with infantry and artillery units in different types of terrain, in order to operate in Vietnam's rough mountainous and jungle conditions.

[6][7] From their base in Luong Son, Hòa Bình Province, the 198th Tank Battalion began their arduous 1,350 kilometers (840 mi) journey down the Ho Chi Minh Trail under constant U.S. air-strikes.

In 1966, Detachment A-101 moved to its first site near the village of Lang Vei, when the United States Marines took control of Khe Sanh Combat Base as part of an American military build-up in South Vietnam's northern provinces.

Since the original site lacked good observation and fields of fire beyond the barbed-wire perimeter, the 5th Special Forces Group commander decided to move the camp to a more suitable area, about 1,000 meters to the west.

[2]: 111  3rd Marine Division intelligence estimated the combat strength of PAVN and Viet Cong forces in the Vietnamese Demilitarized Zone area during this period was 40,943 troops.

[8]: 258  Throughout the night, the combined U.S and South Vietnamese forces held their position, but at dawn U.S. soldiers on the ground called in air strikes and artillery support from the Khe Sanh Combat Base.

[1] On the evening of 23 January, one day after the fall of Khe Sanh village, the PAVN 304th Division moved against their next target, the small Laotian outpost at Ban Houei Sane.

[9] Prior to 1968, Laotian forces at Ban Houei Sane had played an important role in the war, watching PAVN infiltration into South Vietnam from a section of the Ho Chi Minh Trail running through Laos.

[1] After three hours of fighting, Lt. Col. Phetsampou decided to abandon his outpost, so he radioed the Lang Vei Camp and requested helicopters to evacuate his men and their families.

However, as helicopters were unavailable, the Laotians decided to move eastward by foot along Highway 9, in an attempt to reach Lang Vei just across the border in South Vietnam.

The Laotian soldiers of BV-33, with assistance from the new Special Forces team, were given materials to restore the old Lang Vei Camp, where they would remain until further orders were issued from Da Nang.

[2]: 111  The Laotian soldiers and their families brought with them stories of a PAVN attack supported by tanks, which was a cause for concern for Willoughby, because Ban Houei Sane was only 15 kilometers (9.3 mi) away across the border.

On 30 January Willoughby's fears were confirmed when a PAVN deserter, Private Luong Dinh Du, surrendered himself to the U.S. Special Forces in Lang Vei.

[1] From an observation post above the tactical operations centre, Sergeant Nickolas Fragos saw the first PAVN tanks moving along Lang Troai Road, attempting to breach the barbed wire in front of Company 104.

[2]: 119  Soon afterwards, three PT-76 tanks were knocked out by a 106 mm recoilless rifle manned by Sergeant First Class James W. Holt, but the barbed wire in front of Company 104 was quickly overrun by the combined PAVN tank-infantry attack.

Despite the ferocity of the air strikes and artillery fire, the PAVN managed to break through the Company 104 area, forcing the defenders to retreat into the 2nd and 3rd Combat Reconnaissance Platoon positions behind them.

About 800 meters to the west, Sergeant First Class Charles W. Lindewald, an adviser to the Mobile Strike Force, also reported back to Willoughby that the early warning outpost was in danger of being overrun.

From the team house, a group of four Americans and about 50 CIDG soldiers held a quick conference and decided that they would leave the camp through the northern perimeter, where there was no visible sign of the PAVN.

Ultimately, only two Americans and about 10 Vietnamese soldiers managed to escape from the camp, taking refuge in a dry creek bed that offered some cover and concealment.

[2]: 129  In an attempt to save the defenders at Lang Vei, Company C Headquarters in Da Nang tried to call for reinforcements from the Marines at Khe Sanh, but its request was also turned down.

[2]: 132 [3]: 30  After Ashley had formed the Laotian soldiers into a skirmish line, he radioed the forward air-controllers overhead to direct strafing runs on the Special Forces camp to soften up the enemy.

Under the cover of U.S. air strikes, Willoughby and other American survivors escaped towards the old Lang Vei Camp, which was evacuated by Marine CH-46s from HMM-262, which lifted in a 50 man reaction force.

An estimated 6,000 survivors from the old Lang Vei Camp including CIDG soldiers and their families, Montagnard tribesmen and the Laotians, followed the Americans and descended on the Khe Sanh Combat Base.