New organizations, tactics and techniques, as well as new items of equipment were tested in combat throughout the country during 1963. Among the modifications made to the M113s at this time was the fitting of a gun shield to the .50 calibre machine gun. The deaths of at least 14 .50 cal. gunners at the battle of Ap Bac in January 1963 impelled the provision of greater protection. The first gun shields were fabricated locally from whatever materials were at hand. The 2nd ACR made some of soft steel plating from the hull of a sunken ship, but later replaced them with plates from surplus armored vehicles, mainly M3 half-tracks and scout cars. One crew of 4th Armored Cavalry Regiment at Da Nang even fashioned a gun shield from the bumper of a worn-out forklift truck. The 80th Ordnance Depot in Saigon quickly developed the idea and produced drawings and specifications for a standard gun shield. From 1964 these were fitted to all APCs before being issued to ARVN forces.
ARVN units also mounted M1919 .30 calibre machine guns, some with shields but most without, on the sides of APCs to increase firepower. Many M113s were fitted with machine gun turrets mounting twin .30 calibre guns in place of the .50 calibres. These cupolas were popular with ARVN troops, but the .30 calibre was inferior to the .50 calibre for penetrating earth and log emplacements, and the latter remained the standard weapons for APCs throughout the war. Other local modifications were also made with less success, like the mounting of an M8 armored car turret with its 37mm gun on the M113, or the installation of a 57mm recoilless rifle in place of the .50 calibre machine gun.
Unit reorganization and new equipment alone were not enough to bring about a change in the war. New tactics, better leadership, and improved training were needed to complement the increased firepower. When training lagged, overconfidence and poor leadership combined to teach some costly lessons.
The ARVN armored units were not only engaged against the Communist guerrillas, but also in the changes of government in Saigon. On 1 November 1963, the 1st ACR and the vehicles from the Armor School at Thu Duc supported a coup that overthrew the Diem regime. The regular implication of the ARVN armored units in politics led their detractors to name them "coup troops". In the same vein, tanks were called "voting machines". In fact, the rapid expansion of ARVN armored units caused some consternation among the political establishment in Saigon, who knew from bitter experience that they only remained in power at the sufferance of the Armor Command. This situation persisted until the late 1960s when the ARVN armored corps officers became less political and the tank squadrons were used more effectively rather than being deployed in static defense at regional political centres.
In December 1963 two regimental sized armored units were activated. The 5th Armor Group, later re-designated the 5th Armored Cavalry Regiment, and the 6th Mechanized Battle Group, later redesignated the 6th Armored Cavalry Regiment, were both assigned to the ARVN high command as a general reserve. Later, in March 1964, two more mechanized rifle squadrons were formed at the Armor School. They completed their training in October. These additions made a total of fourteen operational mechanized rifle squadrons.
Most American armor advisors were impressed by the technical proficiency of the ARVN units. The singular most consistently praised characteristic of ARVN armored troops was their ability to perform individual and unit maintenance on vehicles and weapons; advisors commended them for keeping equipment operational with very limited support. Without recovery vehicles, armoured units became extremely inventive. Since the supply system of the South Vietnamese Army was universally poor, the armored troopers became adept at scrounging replacement parts. Squadron and regimental mechanics performed such tasks as internal repair of starters, generators, radiators, and carburettors, maintenance normally accomplished by ordnance units with the US Army. Deprived of aluminium welding, troops repaired holes and cracks in the hull of APCs with wooden pegs and cement. Banana stalks and ponchos were used to mend radiators in water-cooled vehicles. Despite an inadequate supply system, the lack of turret or support unit mechanics, and with the only replacement vehicles being in Saigon, units still consistently managed to field over 90 percent of their equipment. Combat maintenance units remained at a high level throughout the conflict.
Even with additional forces and equipment, however, the combat record of the ARVN armored units in 1964 was still uneven. One battle on the Plain of Reeds on 3 and 4 March 1964 ended in a resounding victory for the South Vietnamese and the capture of over 300 Viet Cong. In contrast, on 28 December 1964 the 9th Viet Cong Division seized the town of Binh Gia, sixty-five kilometres east of Saigon. During a battle that lasted several days, the ARVN Ranger and Marine battalions were severely beaten. The armored relief forces were ambushed and they too suffered heavy casualties. This battle was significant for both sides since it marked the general offensive launched by the Communist forces.
Almost at the same time that the Viet Cong began to appear in division-sized units, American forces began deploying in Vietnam. For the next seven years, US forces and their armored units would play the main role in the fighting, relegating the ARVN into so-called pacification missions.
By 1964 the superannuated M24 Chaffee, inherited from the French, had become more of a liability than an effective fighting machine. Spare parts were difficult to obtain and mechanical problems were legion, compounded by the necessity of sending engines to Japan for rebuilding. In January 1965, the old M-24 Chaffees were replaced with the M-41A3. Five squadrons were equipped and trained by the end of 1965. Although the first plan was to turn in the old M-24s, the relics became pillboxes at installations throughout South Vietnam, except for a dozen tanks under control of the South Vietnamese Air Force (VNAF) at Tan Son Nhut. In reality, this VNAF armored squadron was put under the direct command of Vice Air Marshall and Prime Minister Nguyen Cao Ky as a countercoup force. The M-41A3 proved an excellent choice and was popular with the ARVN. Its combination of rugged simplicity, mechanical reliability and responsive handling made it a very battle-worthy machine. The principal criticism of the tank in US service - cramped crew conditions - did not trouble the smaller Vietnamese. The M41A3 proved to be a potent fighting vehicle in Vietnam and gave admirable service in the hands of ARVN cavalry troopers. US sources indicated that more than 506 M-41A3s were delivered to South Vietnam throughout the war.
At the outset the Viet Cong were ill prepared to counter the M113, as this passage from a captured document reveals:
Initially the VC fled when confronted with M113s, which they dubbed 'Green Dragons' from their appearance as they moved rapidly over waterlogged paddy fields belching fire and smoke from guns and engines. As time went by, the VC adapted their tactics to meet the menace. Holes were dug in Delta roads. Improvised explosive devices were placed at defiles and obstacle crossing points. Early in 1963 the Viet Cong were issued with HEAT ammunition for the Chinese Type 36 57mm recoilless rifle (copied from the US M18A1 of Korean War vintage), which soon became their principal heavy infantry weapon. During the year other anti-tank weapons were encountered, including the Polish PGN-2 anti-tank grenade fired from the AK-47 assault rifle and the powerful Chicom Type 52 75mm recoilless rifle (copied from the US M20).
As increased use was made of the M113, so VC anti-tank weapons proliferated, and by 1965 they were issued as low as company level in regular and provincial units. Most formidable of the VC armor defeating weapons was the Soviet RPG-2 and its Chinese derivative, the Type 56. The RPG-2 was superseded by the RPG-7, an improved rocket-propelled grenade of increased lethality and range.
The hollow-charge warhead was capable of penetrating a considerable thickness of armor as long as it struck at or near normal incidence and detonated at the proper standoff distance. M113s sustained approximately one penetration for every seven RPG hits. Hits in themselves averaged about one in eight to ten rounds fired due to the inherent inaccuracy of the weapon. M41A3 penetrations were proportionally less because of its superior ballistic configuration as compared to the slab-sided M113. Statistical analysis reveals that only one vehicle was destroyed for every seven penetrations and casualties were 0.8 per penetration. Nevertheless, this simple, cheap and effective weapon was a constant and serious threat to allied armor throughout the war.
The ARVN armored units continued to expand and were sometimes engaged in important operations. From 19 to 27 October 1965, the 3rd ACR, along with some Rangers, battled through to the relief of the Plei Me Special Forces camp southwest of Pleiku. Although ambushed en route by a PAVN (People's Army of Vietnam) regiment, the task force reached the camp, established a perimeter and stood off a heavy attack. It then counterattacked and drove away the North Vietnamese forces. Nevertheless, the armored troops demonstrated little aggressiveness, content instead to stand and fight as if they were in pillboxes. Coordinated action between tanks, APCs and Rangers was almost non-existent. Leadership and control was still a long way from acceptable standards. Maintenance continued to be a bright spot, though, with all fifteen tanks returning from the fight.
Beginning in 1966, an extensive training program took place to improve the fighting standards of the ARVN armored units. The main obstacle that the US advisors had to overcome was the misuse of the armor. The ARVN senior officers either ignored or did not understand the capabilities of an armored force. The general situation and the effectiveness of the armored forces were only corrected in early 1968.
Plans for the ARVN for the period 1965-1966 called for the formation of one V-100 armored car squadron and ten separate armored car troops and the replacement of units equipped with M-8s and older obsolete vehicles. Three of these troops completed training in May 1965, but structural flaws found in the V100 delayed their use for six months. Four new Armored Cavalry Regiments were created in 1966: the 7th ACR at Dong Ha, the 8th ACR at Ban Me Thout, the 9th ACR at Soc Trang and the 10th ACR at Cu Chi.
Vietnam Tracks, Armor in Battle 1945-75, Simon
Dunstan, Osprey Publishing Ltd., 1982, ISBN 0-85045-472-7