Due to the vulnerability of their supply lines in Phước Long and the surrounding areas, the PAVN in Lộc Ninh and in the Central Highlands, often found themselves isolated from their units in the southern provinces of South Vietnam.

[6] The PAVN had closed surface travel from Saigon to Phước Long by the direct route through Bình Dương Province, during the Easter Offensive in 1972 and the only land access available to the South Vietnamese was via Ban Me Thuot and Quảng Đức.

[7]: 59–60 On 20 July 1974, the PAVN High Command created the 4th Army Corps for the purpose of capturing Phước Long from the opposing South Vietnamese.

[2] South Vietnam's main defensive assets in and around Phước Long included five security battalions and 48 platoons of civilian self-defence forces.

On the same night the military zone of Bù Đốp was also attacked by a company of Viet Cong (VC) special forces from the Phước Bình area.

Due to the heavy rain which flooded the main roads leading to Phước Long, the PAVN decided to postpone further attacks which were planned to take place on 13 December.

[10] On the same day, after a night of encirclement, the PAVN 165th and 201st Regiments, both drawn from the 7th Infantry Division, established control over the Vinh Thien area and the Bù Đăng administrative centre after more than two hours of fighting.

[9] On 15 December, soldiers from the PAVN 429th Special Forces Regiment attacked Bu Na, which was defended by one ARVN company from the 363rd Security Battalion, and an artillery platoon.

However, by the end of the day South Vietnamese defenders around Bu Na gave up, when reinforcements from Phước Long failed to arrive due to the closure of Route 14 by the PAVN.

The ARVN attempted to stage a counter-attack on Bo Duc, but they were defeated by the PAVN 6/165th Regiment, as a result all surviving South Vietnamese units retreated back to the Bà Rá area.

As a result, Đống had to order Brigadier general Lê Nguyên Vỹ to reinforce the areas around Đôn Luân with units taken from the ARVN 5th Infantry Division.

At 10:30 all ARVN units at Đôn Luân capitulated and Major Đặng Vũ Khoái, commander of the 352nd Security Battalion, was captured at Suoi Rat along with his junior officers.

Shortly afterwards Viên received a message from Thiệu which advised Đống not to make discretionary decisions, and to try to maintain the morale of the South Vietnamese soldiers at Phước Long.

The capture of Bà Rá Mountain enabled PAVN units to occupy the high ground areas surrounding Phước Long, where they could direct artillery fire against ARVN positions.

But as soon as the first group of the 81st Ranger Battalion landed on Dac Song, they were quickly decimated by PAVN artillery, with the unit suffering losses equivalent to two companies.

On the following day, the PAVN 4th Army Corps command sent the 201st Regiment, along with ten additional tanks, to reinforce the units already fighting in Phước Long and to cut off the South Vietnamese route of escape, Cach Mang and Dinh Tien Hoang streets were blocked.

At the battle's conclusion, the North Vietnamese claimed they had captured 2,444 prisoners, including 26 officers, 5,000 small arms of various kinds and more than 1,000,000 rounds of ammunition.

The sacrifice of the ARVN in the battle was exemplified by the 250-men 81st Airborne Ranger Battalion, which lost more than 150 soldiers in their last-ditch effort to save Phước Long.

In logistical terms the victory at Phước Long enabled the PAVN to connect their supply lines from the Ho Chi Minh Trail, with bases in the Central Highlands and the Mekong Delta.

[3] In Hanoi, the capture of Phước Long provided the Communist leadership with clear answers about America's commitment to defend South Vietnam, as well as their willingness to re-enter the conflict.

The lessons learned at Phước Long were put into practice during the 1975 Spring Offensive, which ultimately led to the capitulation of South Vietnam on 30 April 1975.

[6] To make matters worse, the United States Congress repeatedly voted against President Gerald Ford's request to give additional aid for South Vietnam.

One month later, Thiệu reinforced his previous message by asking the people of South Vietnam to maximise their support of soldiers on the frontline, stabilise the country's internal situation, and increase economic production.