Operation Shenandoah II was an operation conducted during the Vietnam War by the U.S. 1st Infantry Division to secure and repair Highway 13, South Vietnam from 29 September to 19 November 1967.
Background During the 1967–1968 dry season, II Field Force, Vietnam planned to mount a large-scale offensive to cut the three main infiltration routes into III Corps from Cambodia. In order to build up the necessary forces near the Cambodian border and sustain their operations Highway 13 needed to be opened and secured.
Meanwhile, Central Office for South Vietnam (COSVN) commander General Trần Văn Trà pursued a strategy of attrition using his People's Army of Vietnam (PAVN) and Viet Cong (VC) forces to attack U.S. military units and inflict as many casualties as possible hoping the Americans would conclude the war was too costly and withdraw from South Vietnam. Trà's deputy, General Hoàng Văn Thái planned to use the experienced VC 9th Division, commanded by Senior Col. Hoàng Cầm, to spearhead COSVN's dry season offensive in Bình Long Province. The initial target was the district capital of Lộc Ninh with the objectives of neutralizing the U.S. Special Forces and CIDG camp there and embarrassing the South Vietnamese Government.
Operation
During the first weeks of the operation, the 1st and 3rd Brigades, 1st Division secured Highway 13 between Lai Khê and Chơn Thành District. These forces also swept the Long Nguyen Secret Zone, situated between Highway 13 and the Michelin Rubber Plantation about northwest of Saigon, in Binh Duong Province.
On 29 September, MG John H. Hay ordered the 1st Brigade (1st Battalion, 2nd Infantry Regiment and 1st Battalion, 28th Infantry Regiment) into the northern part of the Zone. On 30 September, the 3rd Brigade (2/2nd Infantry and 2/28th Infantry) was ordered into the southern half of the Zone. Initially the U.S. forces made little contact with the VC. On 2 October, an Army of the Republic of Vietnam (ARVN) unit operating east of Highway 13 near Chơn Thành engaged a large VC formation and took heavy casualties. Documents found on the dead indicated they had clashed with a battalion-sized unit from the VC 272nd Regiment, sent to attack Chơn Thành in order to cover the movement of the 271st Regiment into the Long Nguyen area.
On 4 October the 1/2d Infantry engaged a VC company 9 km southwest of Chơn Thành, killing 12 before the VC withdrew to the west. To pursue the retreating VC, the 1st Battalion, 18th Infantry Regiment was instructed to conduct an air-assault into a clearing located about west of the 1/2nd Infantry, in order to block enemy troops. The 1/18th Infantry landed unopposed, and they immediately set up a standard field position with wire entanglements to protect the base. On 6 October, the 1/18th Infantry's position was hit by VC mortar fire causing little damage. At 18:00 it began to rain and an hour later the VC started attacking the perimeter from different directions, but the attack was repulsed with the support of artillery and mortar fire. By midnight the fight was over. U.S. casualties were 5 killed and 4 wounded. Three weeks later a captured VC soldier from the 2nd Battalion, 271st Regiment, claimed that his unit lost 59 killed and 56 wounded in the attack.
On 8 October, 1/2nd Infantry was moved to Phước Vĩnh Base Camp to act as the division's reaction force. The 2/28th Infantry was then lifted from Lai Khê and landed about northwest of Chơn Thành, and north-west of 1/18th Infantry's position. On 10 October 1/2nd Infantry was deployed into new blocking positions, as VC units were believed to be moving toward the Michelin Rubber Plantation. On 11 October 11, two companies from 1/18th Infantry probed northwards and were immediately attacked by the VC. While under heavy fire, the lead company was ordered to pull back behind a perimeter formed by the second company. As the lead company fell back, artillery and air support were called in to pummel the VC's attacking formation. When the battle was over, 21 VC were found dead, whereas U.S. casualties for the day were 1 killed and 4 wounded. On 13 October, 1/18th Infantry was moved to Phước Vĩnh for rest and refitting.
By mid-October, MG Hay believed the VC 271st Regiment had suffered a major defeat and was ready to withdraw from the Long Nguyen Secret Zone, so he was ready to terminate the operation. However, increased VC activity near the Ong Thanh Stream, which flowed near the Binh Duong-Binh Long provincial boundary, where the 1st Brigade made most of its contacts, had indicated otherwise.
Battle of Ong Thanh
On the morning of 16 October, two companies of the 2/28th Infantry commanded by Lt Col. Terry de la Mesa Allen Jr. left their night defensive position along the Ong Thanh Stream to patrol an area to the southeast covered by thick jungle canopy. After moving about , the battalion found a fortified VC bunker and pulled back to allow airstrikes against the VC positions. When the airstrikes were over, they reentered the camp and a firefight broke out with VC snipers firing down from trees in the surrounding areas. U.S. forces pulled back and artillery strikes were called in against VC bunker positions. They again re-entered the camp, and they discovered the bodies of 17 VC. Moving through the western end of the camp, and another firefight broke out with an estimated 60 VC. Later that afternoon Lt. Col. Allen decided to break contact and return to base, to avoid fighting a battle that could last until the evening. He also called in airstrikes to inflict further damage on the VC.
On the morning of 17 October the 2/28th Infantry renewed their attack against the VC position and at approximately 10:00 they triggered a 3-sided ambush by the 271st Regiment reinforced by 200 soldiers from the VC C1 Company of Rear Service Group 83. At 12:00 the 2/28th Infantry attempted to withdraw but were engaged by intense fire killing Allen among others.
U.S. losses were 64 killed, 75 wounded and 2 missing. VC losses were unknown, the 1st Brigade reported an estimated body count of 101, but the U.S. relief force found only 2 VC dead.
First Battle of Loc Ninh
After clearing the Long Nguyen Secret Zone, the next stage of the operation called for the 1st and 3rd Brigades to secure Highway 13 through An Lộc up to Lộc Ninh 25 km farther north, however II Field Force commander LTG Frederick C. Weyand suspended this phase as it became apparent that COSVN was preparing to launch a major offensive in northern III Corps.
In late September and early October patrols from the Lộc Ninh Special Forces Camp discovered an engineer company from the VC 9th Division building a large hospital on the Sông Bé River several kilometers west of Lộc Ninh and elements of the 84A Artillery Regiment (which operated in support of VC infantry) camped within a few kilometers of Lộc Ninh. Allied intelligence also obtained documents indicating that the 9th Division would begin a major operation in Bình Long Province on or about 25 October. LTG Weyand ordered MG Hay to prepare contingency plans for the defense of the district capitals of Lộc Ninh and Sông Bé.
After midnight on 27 October, under cover of mortar fire, the VC 88th Regiment attacked Sông Bé, while 2 PAVN battalions attacked an ARVN 5th Division base camp several kilometers southeast of Sông Bé. The 200 ARVN defenders held on with air support and eventually forced the PAVN to withdraw. A sweep of the battlefield in the morning found 134 PAVN dead and 2 wounded soldiers: 73 abandoned weapons, including 3 flamethrowers and 10 machine guns, were also found. ARVN losses were 5 killed and 7 civilian laborers were also killed. An ARVN Ranger Battalion and the 1/18th Infantry flew into Sông Bé, but the VC had already withdrawn and the 1/18th Infantry returned to Lai Khê on the afternoon of 28 October.
At 01:00 on 29 October the 9th Division attacked Lộc Ninh. The attack opened with a barrage of 122-mm rockets and 82-mm and 120-mm mortar rounds against the Special Forces camp and the South Vietnamese district headquarters. The defenders responded with their own mortar fire and called for support. At 02:00 VC sappers attacked the district headquarters, detonating satchel charges on the northern perimeter wire clearing the way for 2 battalions of the 273d Regiment. The defenders withdrew into the south of the compound. A pair of U.S. UH–1B helicopter gunships arrived on the scene and began attacking the VC and were soon joined by an AC–47 Spooky gunship which poured fire on VC reserve forces in the nearby treeline. Despite the air support, the situation in the compound remained desperate and the district chief called for a Proximity fuse artillery barrage on his own position which caused devastating losses to the exposed VC. At 04:00 the VC withdrew while under fire by air and artillery strikes. At dawn the ARVN found that some VC had stayed behind in bunkers in the compound and after reinforcements arrived they proceeded to methodically clear out the VC using M72 LAW rockets. 135 VC had been killed in the attacks on Lộc Ninh while the ARVN lost 8 killed and 33 wounded.
On the morning of 29 October, two companies from the 2/28th Infantry and a battery of 105-mm howitzers were flown into Lộc Ninh to set up a firebase at the southwest corner of the airstrip. By 09:50 the battery was operational and conducting preparatory fire for the landing of the 1/18th Infantry 3.5 km to the northwest. The battalion landed unopposed and established a defensive perimeter to establish a firebase. At 12:00, a CIDG company radioed that it had engaged a PAVN platoon 1 km north of the landing zone and Company C 2/28th Infantry was sent to support the CIDG company, hitting the PAVN from behind, killing 9 and scattering the rest. Two more PAVN platoons then counterattacked Company C and Company D was sent in a flanking attack forcing the PAVN to withdraw. 5 PAVN had been killed and captured documents indicated they were from the PAVN 165th Regiment.
On the morning of 30 October the 165th Regiment attacked Company A, 1/18th Infantry, as it was reconnoitering the area around its landing zone. Company D and a CIDG company were immediately sent to assist forcing the PAVN back to a low hill where they took refuge in some shallow irrigation trenches. The U.S. forces called in air and artillery strikes and then the CIDG forces attacked forcing the PAVN into a gully where they were hit by further air and artillery strikes. 83 PAVN were killed and 32 weapons were captured.
MG Hay ordered the 1st Brigade to move its headquarters to Quản Lợi Base Camp to prepare for a renewed attack on Lộc Ninh. Just after midnight on 31 October, rockets and mortar shells began pounding the district compound, the Special Forces camp, and the airstrip artillery firebase. As the barrage ended, helicopter gunships and an AC-47 arrived over Lộc Ninh and began firing on suspected assembly areas. They were met by heavy machine gun fire from the PAVN 208th Anti-Aircraft Battalion. At approximately 02:00 hundreds of 272nd Regiment troops emerged from the treeline on the eastern side of the airstrip. Their attack was met by interlocking fire from the 3 U.S./ARVN positions around the airstrip. A small group of VC made it across the airstrip and fought their way into the district headquarters compound. No follow-up troops were able to advance and they soon abandoned their attack and withdrew. At dawn the 272nd Regiment withdrew east, leaving 110 dead. ARVN/U.S. losses were 9 killed and 59 wounded. The 1/28th Infantry was deployed southeast of Lộc Ninh in pursuit of the 272nd Regiment and killed 11 VC over the next two days, but failed to locate main body of the 272nd Regiment.