The Fifth Division of the Army of the Republic of Vietnam (ARVN)—the army of the government of South Vietnam that existed from 1955 to 1975—was part of the III Corps that oversaw the region of the country surrounding the capital, Saigon.
The Fifth Division was based in Biên Hòa, a town on the northern outskirts of Saigon, and due to the Division's close proximity to Saigon was a key factor in the success or failure of the various coup attempts in the nation's history. As a result, the loyalty of the commanding officer of the Division was crucial in maintaining power.
History 1960-1964 The division was originally established as the 3rd Field Division and redesignated as the 5th Infantry Division in 1960.
In the 1960 South Vietnamese coup attempt, the loyalist Colonel Nguyễn Văn Thiệu used the division to storm into Saigon to save President Ngô Đình Diệm.
However, in the successful coup attempt of 1963, Thiệu rebelled and the division along with the rest of the III Corps of Tôn Thất Đính, attacked Saigon. Thiệu himself led the successful siege on Gia Long Palace. As a result, the leading generals made Thiệu a general.
On 31 December 1963, while Thiệu was out of the country, the division probed the VC's Boi Loi and Long Nguyen bases in Tay Ninh and Binh Duong provinces. Ten battalions participated and a mechanized troop, a company of tanks, a river assault group, three platoons of artillery, and aircraft backed them. At noon, a VC company lured the 32nd Ranger Battalion north across the Thi Tinh River where heavy fire from an entrenched battalion pinned it down. Unable to maneuver, the battalion directed strikes by 155mm howitzers and US Army helicopter gunships without apparent success. At 17:30, the Rangers launched an assault, but intense fire from their front and a new VC unit on their western flank stopped them. At 18:00, the Rangers withdrew to the southeast, but a VC battalion appeared to block their way. After repulsing two attacks from this new threat, the Rangers, now surrounded on three sides, escaped into dense jungle to the east. Fortunately, they had no further contacts, and by the time reinforcements finally arrived at noon on 1 January 1964, the VC were gone. The sweep continued until the fourth. The ARVN lost nine killed, 45 wounded, 31 missing, and 32 weapons lost mostly from the 32nd Rangers.
In January 1964, III Corps' senior adviser, Colonel Wilbur Wilson recommended that the junta remove Thiệu from command of the 5th Division. In Wilson's opinion, Thiệu focused too much on politics to the detriment of his duties. The junta did nothing, but junta leader General Nguyễn Khánh sent Thieu to the Joint General Staff (JGS) not as a punishment, but as a reward for his support. On 1 February, Khánh named a new division commander, Colonel (soon to be Brigadier general) Dang Thanh Liem.
Wilson found Liem to be "pro-American," which was the only good thing he could say about him. Otherwise, Wilson considered Liem: "stupid... immature and at times outright childish. He is indecisive and lacking in leadership. He is against fighting the Viet Cong with small units or with forces in equal strength to the Viet Cong; he requires an uneven ratio in his favor. On operations he holds foremost in his mind the fear of taking casualties. He is limited in his tactical knowledge which has led many of the division officers to question his military competence... His prosecution of the counterinsurgency effort can be characterized as less than energetic."
Wilson began lobbying for Liem's removal almost immediately. When COMUSMACV General Paul D. Harkins went out to counsel Liem in March, Lien reportedly told him "that he did not want any further advice; that he had been fighting the war for eighteen years and knew what had to be done." Harkins replaced the division adviser in the hope of promoting better relations, but the new man was no more successful in getting Liem to take advice. Subsequent efforts by MACV to either influence Liem or remove him had little effect.
At 01:00 on 6 February, the VC overran an outpost and three hamlets at Ap Ben Cau, 19km south of Tây Ninh, killing 65 of the 188 Self-Defense Force and militia defenders and capturing 50 weapons. The VC then fortified the hamlets waiting for a government relief force. The Americans urged a vigorous response, but the division's deputy commander was reluctant to act in Liem's absence. After much cajoling, he sent 300 men from the 2nd Battalion, 9th Infantry, an understrength Civil Guard company, and two 105mm howitzers. Leading the force was the regiment's executive officer, Captain Thai. Accompanying him were three advisers led by Captain Donald S. Cunningham. Upon approaching the hamlet of Ben Cau, Cunningham decided the VC had left and urged Thai to pursue. When Thai refused, he shamed him into advancing by threatening to scout the hamlet by himself. The battalion took up a position west of the walled hamlet when VC machine guns opened fire. Thai had allowed the Civil Guard company to advance on the town by itself from the south. Not until the company was 30 meters inside did the VC open fire, killing the commander and five other soldiers. As the troops retreated out the gate, Cunningham spotted them and, thinking they were VC, called down six artillery rounds that killed seven more of them. Cunningham suggested that Thai ask for air support, which first came in the form of two US helicopter gunships. After antiaircraft fire drove off the helicopters, Cunningham asked Thai to let him use a recoilless rifle to knock out a machine gun, only to learn that Thai had left the unit’s heavy weapons behind. By now, two AD–6 fighter-bombers were overhead. Thai kept them loitering for an hour before acquiescing to Cunningham’s demand that he employ them against the wall. After the bombs missed because of poor guidance from the ground, Cunningham defied Thai and crawled forward to a better viewing position from where he directed a successful rocket strike against the defenders. Thai however refused to advance, leaving the fighter-bombers to pummel Ben Cau, ignoring not only Cunningham's advice, but also three orders to attack radioed in from the battalion commander. Meanwhile, at division headquarters US advisers argued for the Vietnamese to send the entire 9th Infantry Regiment and an airborne battalion. Eventually the acting division commander agreed to send just one company of his own and to ask the JGS for the airborne battalion. The JGS consented to two companies. A shortage of helicopters in the area meant that the Americans could land only one unit at a time. At 16:00 12 US CH–21 helicopters landed the first of the two airborne companies north of town. The unit faltered under withering fire. Most of the paratroopers withdrew, but Airborne adviser Major Daniel L. Baldwin rallied ten men who stood their ground until their ammunition was exhausted. Already wounded twice himself, Baldwin then carried a seriously wounded paratrooper as they withdrew to safety. At 17:00, US Army helicopters delivered the 5th Division’s reconnaissance company, and at 17:50, they returned to land the second airborne company. Neither unit could make any headway. As darkness descended, the firing stopped, all except the howitzers that continued a desultory bombardment throughout the night. At 06:30 on 7 February, the 2nd Battalion entered Ben Cau. The VC had withdrawn 5km away to Cambodia overnight. The soldiers found a shattered community. A senior US adviser reported that the VC had dug 1,000 foxholes into the village berms, making anything but an assault by tanks impossible. Such an option was not available, as the division had sent all its tanks to Saigon a few days earlier to support Khánh's coup, and they had not yet returned. Later analysis determined that the VC had consisted not of a battalion of only 500 as first reported, but of the entire 1st Regiment with between 1,000 and 2,000 men. A JGS study based on captured documents concluded that the VC lost 61 dead and 105 wounded. South Vietnamese casualties amounted to 27 dead, 66 wounded, and 34 missing. The study reported 27 dead and 29 wounded civilians, likely an undercount. Aircraft and artillery had destroyed 670 houses, leaving up to 4,000 people homeless. The 5th Division gave Thai a battalion command.
On the night of 3–4 April 1964, the VC 1st Regiment returned from its Cambodian sanctuary and attacked Phuoc Tan New Life hamlet 2km from the border. The assault, which destroyed 186 houses, was mostly a pretext for setting a trap for the expected relief force. Captain Cunningham accompanied that force, which consisted of three division infantry companies, an ARVN Special Forces company, and a Civil Guard detachment. Cunningham was unable to persuade the ARVN to bring their 81mm mortars to a location from which they could fire in the coming battle. He likewise failed to dissuade the force commander from marching down a road into a predictable ambush. Once the firing began, however, his counterpart enthusiastically embraced his help in getting air and artillery support. The aid nearly resulted in disaster when the A-1s mistook the column for the enemy and dropped napalm just 100 meters from the command group. Surrounded on three sides by VC armed with recoilless rifles, mortars, and machine guns, the troops fell back as artillery mistakenly fired into a hamlet rather than at the VC positions. Four US Army helicopter gunships then arrived to hit the VC with rockets and machine guns. Later, Cunningham got the supporting 155mm howitzers to adjust their fire to be more effective. By nightfall, air and artillery fire had enabled the task force to extricate itself. A JGS study based on captured documents reported VC losses as 63 killed and 197 wounded. The South Vietnamese lost 25 dead, 22 wounded, and two missing. VC fire wounded six American advisers and aviators.
On 12 April Liem launched Operation Chinh Nghia 29, a six-battalion incursion into War Zone C. Liem only informed his senior advisor, Colonel McKnight, 11 hours before it began, a practice Vietnamese officers employed when they did not want US input. Battalions advanced in single file toward objectives that McKnight thought Liem had drawn to allow the VC to escape. Because of poor planning, two mechanized companies sat idle for 18 hours when government helicopters failed to bring them water. The vehicles advanced only after MACV made an emergency delivery using U.S. helicopters. Similarly, a battalion commander refused to move for six hours after a soldier became wounded and Vietnamese helicopters did not show up to evacuate the man. By the end of the operation, the division had suffered 11 casualties and the VC six. Wilson called the affair a "classic example of a grandiose 'safari' operation... which is contrary to the philosophy and direction of the Chien Thang plan, adversely affects province pacification, and flouts U.S. advice."
In his April monthly report, Wilson wrote: "The conclusions which may be drawn, are that large-scale military operations, as conducted by the 5th Division, produce negligible results, do not support pacification plans, and actually have set back the pacification time schedule in some provinces by as much as ninety days... If military forces were properly positioned and employed in the pacification effort, and if military forces would react more vigorously to VC attacks, accelerated progress could be expected in pacification of the corps tactical zone.” When Wilson and Westmoreland once again lobbied the corps commander and Khánh to replace Liem, they received pledges to do so, but no immediate action.
In June, after months of complaining by MACV, Khánh removed Liem, replacing him with Brigadier general Hao Cao Hon. McKnight soon praised Hon, for having an “outstanding grasp of the concept of pacification and a practical, logical approach to executing the pacification plan."