For 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.

The initial target was the district capital of Lộc Ninh in order to neutralize the U.S. Special Forces and CIDG camp there and to embarrass the South Vietnamese Government.

These forces also swept the Long Nguyen Secret Zone, situated between Highway 13 and the Michelin Rubber Plantation about 56 kilometers (35 mi) northwest of Saigon, in Binh Duong Province.

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.

The 1/18th Infantry landed unopposed, and they immediately set up their standard field position with wire entanglements to protect the base.

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.

[3]: 353 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, which was covered by thick jungle canopy.

At 12:00 the 2/28th Infantry attempted to withdraw which quickly descended into chaos as the U.S. forces were pursued by intense fire killing Allen among others.

[3]: 361 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.

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.

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.

Despite this 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.

[1]: 55–6 MG Hay ordered the 1st Brigade to move its headquarters to Quần 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.

A small group of VC made it across the airstrip and fought their way into the district headquarters compound, however as no follow-up troops were able to advance they soon abandoned their attack and withdrew.

At dawn the 1/18th policed the perimeter finding 263 VC dead while drag marks and blood trails suggested their losses were even higher.

[1]: 60 On 6 November the 1/26th Infantry moved to a new firebase northeast of Lộc Ninh and began probing east towards where the 272nd Regiment was believed to be regrouping.

[1]: 60–1 On the morning of 7 November with Company A remaining to guard their firebase, the rest of 1/26 Infantry left to patrol a dirt road bordered by a rubber plantation.

Captain Dobbins assumed temporary command of the battalion, calling in air and artillery strikes to cover the unit as it withdrew to a more defensible position.

[1]: 62 On the morning of 6 November, elements from the 275th Regiment ambushed a company from the ARVN 5th Infantry Division south of Sông Bé.

[1]: 62 On 25 November elements of the 275th Regiment attacked the ARVN camp south of Sông Bé in a 4 hour long firefight, resulting in more than 100 VC dead.

[1]: 62–3 On 26 and 28 November CIDG troops from Bo Duc 20 km northwest of Sông Bé observed unidentified PAVN/VC forces moving through the area.

[1]: 64 Over the following week, Allied patrols skirmished with VC forces around Bo Duc and each night mortar shells landed in the town.

As the full weight of U.S. air and artillery support was brought to bear on the VC they began to withdraw at 03:00 leaving 49 dead while U.S. losses were 4 killed.

[1]: 64 Between 25 November and 8 December, the PAVN/VC had lost at least 400 men and possibly up to twice that number at Sông Bé, Bo Duc and Bu Dop.

[1]: 66–7 Just after midnight on 3 December, Hoa sent his 1st Battalion, 141st Regiment into action against another night defensive position 3 km south of the 24 November attack.

[4] Defending the base was Company A, 1/18th Infantry and Troop A, 1st Squadron, 4th Cavalry with 3 M48A3 tanks and 4 M113s dug into fighting positions around the perimeter.

This article incorporates public domain material from websites or documents of the United States Army Center of Military History.