Quang Duc Province was important commercially for its vast timber resources and militarily for both sides in the war because of the lines of communication that passed through it. After the
People's Army of Vietnam (PAVN) had closed surface travel from
Saigon to
Phước Long by the direct route through
Bình Dương Province, the only land access available to the South Vietnamese was via
Ban Me Thuot and Quang Duc. As far as the PAVN was concerned, Quang Duc was essential to the extension of its Route 14 out of
Mondulkiri Province,
Cambodia, and
Darlac Province, South Vietnam. Because
Army of the Republic of Vietnam (ARVN) forces controlled
Highway 14 as far south and west from Ban Me Thuot as the
Tuy Đức crossroads (), the PAVN's new Route 14 had to pass through Cambodia and reenter South Vietnam in that salient of Mondulkiri Province that juts into Quang Duc near Bu Prang. The site of the abandoned U.S. Army Special Forces
Bu Prang Camp was perched atop a high, forested ridge astride Highway 14 near the Tuy Đức crossroads at the Cambodian border. Before reaching the Phuoc Long border of South Vietnam's
III Corps, Highway 14 was joined at the hill town of Kien Duc () by Local Route 344, coming over from the Quang Duc Province capital of
Gia Nghĩa. This road junction was vital because its control provided an alternative route from Ban Me Thuot through Dak Song and
Gia Nghĩa on Provincial Route 8B. Important as well was the road junction at Dak Song (), where Provincial Route 8B left Highway 14. Until mid-May 1973 when the PAVN's projection of its new line of communication reached Bu Prang and while the South Vietnam's access to Phước Long through Quang Duc remained unthreatened, neither side paid much attention to Quang Duc. ARVN engineers were working on local roads, primarily to improve access to the timber forests in the northeast section of the province, and the only PAVN activity of any note was mining to harass and delay this project. Only three
Regional Force battalions were located in the province, supported by six 105-mm. howitzer platoons (12 guns), which had had no occasion to fire since the 28 January ceasefire. Additionally, 27
Popular Force platoons were scattered about the province. These were nearly all
Montagnards, and the province population was 60 percent tribal. Around the beginning of May, a Regional Force patrol, moving out from its outpost near Bu Prang made contact with a PAVN reconnaissance party and killed four. The rest of May and June were quiet until PAVN harassment of the RF positions around Bu Prang began in early July, evidently in response to the unusually aggressive patrolling ordered by Colonel Nguyen Hau Thien, Quang Duc's province chief. Mortar attacks, accompanied by some light infantry probes, continued through July, as did RF forays into the old Bu Prang positions on the border west of the Tuy Đức crossroads. In the last week of August, Thien tried a reconnaissance in force with two RF battalions. Both met heavy resistance short of their objectives on the border and returned to camp. This inconclusive skirmishing took on an ominous note in early September when the first evidence appeared disclosing that
COSVN had sent two battalions of its 271st Independent Regiment from southwest of
Tây Ninh up to Quang Duc. The presence of a PAVN main force regiment was a new and dangerous development in Quang Duc. Thien asked for reinforcement and was given an RF battalion from Darlac Province. He complained about the poor performance of the Darlac battalion, and II Corps commander General
Nguyễn Văn Toàn agreed to replace it with another battalion from
Khanh Hoa Province. This gave Thien a force of four RF battalions, which he located at the mutually supporting bases of Bu Prang and Bu Bong (), each with a platoon of 105-mm, howitzers. The 271st Independent Regiment had been roughly handled by the ARVN and
Republic of Vietnam Air Force (RVNAF) in the early months of 1973 in marsh and ricelands along the
Vàm Cỏ Đông River and the Cambodian border in
Hậu Nghĩa and southern
Tây Ninh Provinces. COSVN had pulled it back to Cambodia in April for reorganization and recuperation. Afterwards the regimental headquarters and two of its battalions, the 8th and 9th, were trucked to
Bù Đốp Camp in northern Phước Long Province, while the other, the 7th, was sent to operate under
Long An Province authority. Leaving Bù Đốp, the 271st marched through
Bù Gia Mập District and arrived northwest of Bu Prang in late August, ready to assist in the defense of the new line of communication and to deny the ARVN use of Highway 14 in the border region. Successive attempts by the Quang Duc territorials failed to gain any ground west of the Tuy Đức crossroads, while the rest of Quang Duc Province remained relatively quiet. Meanwhile, PAVN preparations for the Quang Duc campaign continued. A task force headquarters, designated Unit 95, was established at Bù Đốp, and the PAVN 205th Independent Regiment was assembled there for movement to Quang Duc. The 205th had been operating since the ceasefire in South Vietnam's III Corps, and before moving to Bù Đốp it had been in northern Bình Dương Province east of the
Michelin Rubber Plantation. Three more maneuver elements joined the task force at Bù Đốp before its composition was complete: the 429th Sapper Regiment, the 46th Reconnaissance Battalion, and a tank battalion (probably the 20th) from the COSVN 26th Armor Group. Artillery support was provided by the 208th Artillery Regiment, 69th Group, COSVN, which had been operating in
Bình Long Province. Antiaircraft artillery, including 23 mm automatic cannons, joined the force as well as a detachment equipped with
SA-7 antiaircraft missiles. Unit 95 had reached division strength, but this was not yet realized at South Vietnam's II Corps headquarters. Given the meager defenses in Quang Duc, it was surprising that the PAVN leadership committed a force of such overwhelming size. The fact that it did so appeared to reflect the inadequacy of PAVN tactical intelligence and a respect for South Vietnamese capabilities. Such a commitment also underscored the importance attached to the principal objective-construction and protection of the line of communication. Much later South Vietnamese intelligence officers discovered that continued offensive operations by the PAVN's Quang Duc task force were designed to draw South Vietnamese forces into the province and keep them occupied, thereby reducing the forces available for employment against the PAVN's B3 Front. By the end of September 1973, reconnaissance and survey parties from the 208th Artillery Regiment had selected firing positions and observation posts near the Tuy Đức crossroads at Bu Prang, Bu Bong and Kien Duc. Firing batteries moved into Quang Duc by the end of October with their 85 and 122 mm field guns and 120mm mortars. To ensure consistency in survey and firing, the only maps authorized for use in the 208th Artillery were the 1:50,000 series printed in Hanoi. The PAVN 205th Infantry Regiment, with the 429th Sapper Regiment attached, arrived in assembly areas near Bu Prang in mid-October and on 23 October the 208th Artillery began a five-day rehearsal preparatory to the attack. Meanwhile, the 271st Regiment with the 46th Reconnaissance Battalion moved toward Dak Song. ==Battle==