In the coup attempt of 1960, the loyalist Colonel Huỳnh Văn Cao used the Division to storm into Saigon to save President Ngô Đình Diệm.
The Division scored the biggest successes of the military campaigns of 1962, along with the Civil Guard and Self Defense Corps, killing more than 2,000 VC fighters and leaving thousands of others cut off from supplies.
This behavior initially mystified the division's US adviser Lieutenant Colonel John Paul Vann, who directed much of the unit's activity, who was attempting to build Cao into an aggressive commander.
His solution was to fill the ARVN with Catholic political cronies and friends like Cao, Lê Quang Tung and Tôn Thất Đính, who had little military ability, but were very likely to help stop a coup attempt.
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.
"[6]: 116 In 1967 Civil Operations and Revolutionary Development Support (CORDS) advisers found the Division's battalions charged with area security missions were more concerned with their own static defenses than with protecting nearby villages and hamlets or with chasing the local VC.
[6]: 252 Assessing General Thanh they found that "his personal cautiousness and reluctance to push the battalions [those in securing missions] into more offensive activities... difficult to understand," claiming that he discouraged the initiative and aggressiveness of his subordinates."
Tactical advisers, they reported, claimed that the army units contributed little more than their "presence" to local security; were idle most of the time; and, when aroused, were content with "merely chasing the VC and showing the flag."
"[6]: 333 From 12 September to 7 October 1967 the Division participated in Operation Coronado V with the US Mobile Riverine Force (MRF) against the VC 263rd Battalion in Định Tường and Kiến Hòa Provinces.
[8]: 130–5 From 7 March to 7 August 1968 the Division participated in Operation Truong Cong Dinh with the MRF to reestablish South Vietnamese control over the northern Mekong Delta in the aftermath of the Tet Offensive.
As these troops hastily occupied the evacuated American facilities at Đồng Tâm Base Camp and elsewhere, they had little opportunity to familiarize themselves with the local enemy and terrain.
US Corps-level advisers believed that its shortcomings could be easily remedied or, at least for the time being, balanced by the increasing mobility of the neighboring 9th Division, which General Thanh had withdrawn from its area security missions and began using it as the Corps' reaction force.
The permanent withdrawal of RF and PF from exposed positions balanced this disadvantage somewhat, in that General Nam less frequently had to dispatch troops in what were often futile but costly attempts to rescue besieged outposts; he could select areas of deployment more likely to result in combat with major units or large infiltrating groups.
Employing advantages of surprise, superior mobility and firepower, including effective coordination with the RVNAF, the Division was usually the clear winner in that kind of encounter.
[10]: 90–6 In April 1974 during the Battle of Svay Rieng the Division moved a forward command post into Mộc Hóa and was controlling the operation of two task forces then committed in the Elephant's Foot area of Cambodia.