On 28 December 1962, US intelligence detected the presence of a radio transmitter along with a sizable force of Viet Cong (VC) soldiers, reported to number around 120, in the hamlet of Ap Tan Thoi in Dinh Tuong Province, home of the Army of the Republic of South Vietnam (ARVN) 7th Infantry Division.

However, Viet Cong forces anticipated a major attack from the South Vietnamese government from a variety of sources including movement of supplies, an undercover VC agent, and decoded radio communications from the ARVN.

Small-scale military actions, which would eventually escalate into the Vietnam War, started in the late 1950s, when South Vietnamese President Ngo Dinh Diem instituted an anti-Communist campaign aimed at rooting out "left behind" Viet Minh forces.

They had scored the biggest successes of the military campaigns of 1962, killing along with the paramilitary and Civil Guard and Self Defense Corps, more than 2,000 VC fighters, and leaving thousands of others cut off from supplies.

After a skirmish on a highway that resulted in a small number of South Vietnamese casualties along with several trucks destroyed, Cao was called to Saigon and reprimanded by Diem.

Upon his return, Vann and his group of advisers were forced to end the joint planning sessions that had been so successful earlier, and action essentially wound down in their region.

[19] An operations plan suited for an attack on a small enemy formation was drafted by Ziegler, an adviser to Dam and the command staff of the 7th Infantry Division.

[21][note 1] The M113 carriers and the infantry company could act as both a mobile reserve and a reaction force, so it was positioned where it could be shifted to the contact area if the VC began to retreat.

The combined companies were supported by approximately 30 local force soldiers from Chau Thanh District who served as scouts, ammunition bearers, litter-bearers, and emergency replacements.

[24] In the days before the battle, Hoang anticipated a major attack from the South Vietnamese government, as VC intelligence agents in Dinh Tuong had reported the arrival of 71 truckloads of ammunition and other supplies from Saigon, about 65 kilometers (40 mi) to the northeast.

[22] In addition, with the information provided by Pham Xuan An, a well-connected journalist and undercover VC agent in Saigon, Hoang's soldiers conducted last-minute anti-helicopter and anti-M113 training by studying US weaponry and South Vietnamese plans and manuals.

Because of the delay in the arrival of the regular South Vietnamese army units, two Civil Guard battalions of Task Forces A and B—under the command of Dinh Tuong provincial chief Major Lam Quang Tho—were left to march against enemy positions by themselves.

[31] Dam asked Vann, who was circling the battlefield aboard an L-19 reconnaissance aircraft, to reconnoiter possible landing zones on the east and west sides of Ap Bac where additional reinforcements could be inserted to launch their attacks.

[31] However, in the early phases of the war, command relationships between US military units were not well-established, and American aircrews tended to disregard the instructions of advisors, especially Vann, who was regarded as domineering.

The US pilots landed their helicopters 200 meters (660 ft) west of Ap Bac, where they were hit multiple times by VC machine gun and small arms fire.

Vann then radioed Captain James B. Scanlon—senior adviser to the ARVN 2nd Armored Cavalry Regiment—and told him that four US helicopters had either been destroyed or immobilized about 1,500 meters (4,900 ft) southeast of the regiment's position.

Shortly afterward, Ziegler returned with Dam's permission, and Ba was ordered to move his M113 carriers toward the white smoke rising from the burning hamlet.

However, in contrast to previous engagements, VC commander Hoang had ordered the soldiers of the 261st and 514th Battalions to throw everything they had at the South Vietnamese, as retreat through the muddy rice fields would result in certain death.

[42] Cohesion and morale among the crews of the armored formation quickly deteriorated as South Vietnamese sergeants, who served as both commanders and machine gunners of the carriers, were killed and were replaced by less experienced, poorly trained men.

[43] By that stage, Vann was frustrated by the Civil Guard soldiers of Task Force B because they appeared to be in no hurry to reach Ap Bac, as they searched one house at a time while marching up from the southwest flank of the battlefield.

[45] In his final effort to defeat the VC, Vann flew into Tan Hiep and asked Cao to deploy an airborne battalion on the east side of Ap Bac, the most logical retreat route for the Viet Cong.

Vann hoped to trap the Viet Cong inside the hamlets by blocking their retreat routes on all sides and annihilating them using an elite battalion of South Vietnamese paratroopers.

[48] Late in the afternoon, a flight of C-123 Providers, with about 300 South Vietnamese paratroopers aboard, closed in on their objective and quickly drew machine gun fire from the hamlet.

The eastern flank remained open, and he ordered both elements of the 261st and 514th Battalions, exhausted and low on ammunition, to assemble at the south end of Ap Tan Thoi.

Cao would not approve the use of flares because it could expose the airborne battalion's night defensive positions, and instead ordered 100 rounds of artillery to be fired at a rate of four shells per hour.

Moyar (2008) argues that Harkins' resolutely optimistic assessments based on conventional doctrine avoided recognizing shortcomings in tactics and battle readiness and in the arrangement under which ARVN commanders and their American counterparts and advisers were operating.

Against overwhelming odds, the VC had achieved their first de facto victory; they had successfully held off well-equipped ARVN forces supported by artillery and armored units as well as by American airpower.

For individual VC soldiers, the battle demonstrated they could defeat nominally superior ARVN forces, well equipped as they were with up-to-date military hardware and significant support and funding from the United States.

Politically, the VC 261st and 514th Battalions were able to exploit the prestige gained from having inflicted disproportionate losses on the ARVN forces to exercise greater influence in their areas of operations.

[1] Despite the initial success of the Strategic Hamlet Program and the intensified military operations of 1962, the events at Ap Bac placed additional pressure on Diem's government because they showed it was not prepared to cope with the resurgence of the VC, particularly in the Mekong delta.