Tanks rarely feature in Hollywood movies about the Vietnam War (Full Metal Jacket is the only exception that comes to mind), so you might be forgiven for thinking they didn’t play any role in the conflict. In fact, several armored vehicles were used by American and AVRN forces quite effectively there, as covered in this video from the UK Tank Museum:
The main armored vehicles used were:
It was the US Marine Corps that insisted on bringing them to Vietnam. “Deep ditches and steep grades are no problem for the Patton 48.” The M48 A3 had 110mm of frontal armor, but probably more important for its service in Vietnam was the construction. It’s cast, not welded. And this proved invaluable. The communist forces regularly used improvised anti-tank mines, often made from unexploded US ordinance, and the curved underside of the M48 was effective at deflecting the blast of such devices.
On top of that, the M48’s 90mm main gun, plus 50 cal and M60 secondary armament could lay down a withering field of fire, either in support of infantry in the open or in perimeter defense. It didn’t take the US Marine Corps long to prove the M48’s worth. In Operation Starlight in August 1965, the Marines destroyed the first Vietcong regiment on the Vatang Peninsula. A report on the action stated that tanks were the difference between expected heavy casualties and the light casualties we actually took.
By 1966, operations like Hastings and Prairie proved that tanks and marines working in close cooperation was the best way to destroy VC strong points and slash enemy supply routes in wide aggressive sweeps. Despite some continuing reluctance from MACV [Military Assistance Command, Vietnam], tanks were proving far more useful than previously thought.
Another major challenge in Vietnam was ambush. Communist forces would create killing zones up to a kilometer long stretching along key highways. They planted improvised mines to disable lead vehicles and anti-personnel mines and punji spikes at the side of the road to take out infantry dismounting from trapped and stationary vehicles. Once again, tanks proved themselves a huge asset in combating the problem. The M48s would place themselves front and rear of the convoy. The tanks at the rear would have their turrets facing after. If the convoy was attacked, the tanks could often ride through any initial blast or push damaged vehicles off the road, allowing the convoy to keep moving. The armor would then cloverleaf, swinging out from front and rear to envelop the enemy. If all went to plan, they could quickly turn the tables on the attackers as their firepower came into play.
Another counter ambush tactic was the thunderun. A pair of Pattons would take up position either side of the road with one track on the road surface and the other on the verge. They would then race ahead of the column, hosing down likely ambush sites. If they hit a mine, it seldom did more than throw a road wheel. And if they made it through unscathed, the route was considered safe for soft skin vehicles to follow.
As troop numbers grew, the army too began to deploy M48s in a fire support role. Either indirect fire, a substitute for artillery, or in a direct fire role using HE against enemy bunkers. In perimeter defense, tanks would be dug in behind an earth or sandbag berm, flanked by infantry and foxholes, and with a belt of overlapping trip flares, barbed wire, and claymore mines in front. From these defensive cocoons, the tanks could stand firm against human wave attacks, often with the help of one of the most controversial tank munitions ever devised: The beehive round.
The 90mm beehive or M580 AP anti-personal tracer to give it its full title was brutal. It contained 4,200 1/2 in., 5g razor sharp steel flechettes along with a time fuse and bursting charge. The crew would set the detonation range anywhere from 0 to 4,300 m. When the charge went off, the cloud of flechettes formed a 300 m long cone, a deadly swarm carving through jungle cover, wire imp placements, and attacking infantry with devastating effect. The nickname beehive came from a buzzing sound the flechettes made in flight. One M48 gunner described the round’s detonation as like God fired a shotgun.
But the most numerous and arguably effective AFV on the Vietnam battlefield wasn’t a tank at all. It was this, the M113 armored personnel carrier. To the grunts on the ground, it was simply known as “tracks.” M113s were supplied to the South Vietnamese even before the US ground intervention began. And low on armor, the ARVN had to make use of whatever they could get their hands on.
Designed to be air portable, the M113 had aluminum armor. It weighed just 12 tons, had a top speed of 42 mph, was amphibious, had a crew of two, and it could carry up to 11 infantrymen. As an armored personnel carrier, the M113 was essentially a battle taxi designed to drop off its passengers and perhaps provide a bit of fire support from its pintle-mounted 50 cal. However, the ARVN hadn’t read the owner’s handbook. Rather than using M113s as APCs, they set about turning them into ersatz tanks. By adding extra M60 machine guns, recoilless rifles, and mortars.
We’ve seen similar upgrading and front-line use of M113s by Ukraine.
South Vietnamese troops used M113s in an armored assault role. To some extent, this worked. The M113’s mobility and amphibious capabilities were a godsend amongst the rivers, marshes, and rice patties. If a single vehicle couldn’t make it through, the ARVN created daisy chains, linking multiple M113s with steel hawsers. If one got stuck, the others would pull it out.
The problem was that 38 mm of aluminium wasn’t enough to keep out heavy machine guns, let alone RPGs. And with the earlier M113s that were supplied to the ARVN, they were petrol-driven, which meant that they burned a whole lot easier. Once they got over their initial fear of the Green Dragons, the VC realized that all they had to do was pepper the M113s with fire when they appeared and something bad was likely to happen to the ARVN on the inside. Multiple RPG hits would result in a penetration while the top cover gunners were horrendously exposed to small arms fire. In a single action Ap Bac on the 2nd of January 1963, 13 were killed.
With this experience, the vehicles were adapted with the creation of improvised weapon shields. Later formalized as one of the most iconic vehicles of the Vietnam War, the M113 AAV, the armored cavalry assault vehicle had extra belly armor to protect against mines, plus beefed up side armor. The 50 cal and the additional two M60s all had gun shields added to protect the crew. Suddenly, the battle taxis had real teeth, and the US forces started using them in an equally aggressive manner. Perfect for reconnaissance and mobility in the open terrain of the Mekong Delta and rubber plantation. The VC had nothing to match its firepower.
At Ap Bau Bang in March of 1967, the US First Infantry ambushed by Vietcong forces used AAVs in a wagon wheel formation, firing in all directions to break up enemy assaults. During the iconic siege of the Marine Corps base at Khe Sanh, the AAVs used their mobility and firepower to carve routes into the base, allowing infantry and engineer units to lift the blockade. Not bad for a little vehicle that was essentially modified on the hoof and operating way beyond its original combat purpose.
But perhaps the strangest and in its niche most effective vehicle on the battlefields of Vietnam was the M50 Ontos. Ontos is the Greek word for thing, which is certainly less of a mouthful than its official title of Rifle Multiple 106mm Self-Propelled M50, but also an apt name for such an extraordinary looking vehicle.
It does indeed look pretty funky.
“The Marine Corps shows off its newest weapon. A speedy tank destroyer bristling with six powerful recoilless rifles, four smaller spotting rifles, and a machine gun. The Marines call it the Thing.”
The Ontos is small, only 12 1/2 ft long and lightweight at 9 1/2 tons, making it easy to move by air. Yet despite its diminutive size, the Ontos bristled with six M40 106 mm recoilless rifles with a 50 caliber spotting rifle on each side. They could fire a mixture of heat, HE or beehive rounds. For the three-man crew, the biggest challenge was reloading. The loader was holed up in the back of the Ontos and had to exit the vehicle through a hatch and reload the 106s from the outside. Not much fun in the heat of battle.
Despite this, the vehicle’s combination of mobility with ferocious firepower made them devastating in the right setting. Only 300 were built, but they punched way above their weight. In Hue City during the 1968 Tet Offensive, US Marines stood in awe as the Ontos weaved through the tightest urban environments, knocking out walls and cutting down entire squads of enemy soldiers. Such was the reputation of the Ontos that sometimes all that was required was for a 50 cal sighting rifle round to be fired into a building for the North Vietnamese to abandon the position. In the words of one veteran of Hue, “It was ugly, loud, and dangerous. Just what we needed.”
The Ontos would also play a significant role in killing an entirely different set of commies in the Dominican Civil War in 1965.
American M48s would go on to destroy North Vietnamese T-54s during the full-scale invasion of the south, but by then the American withdrawal meant the writing was on the wall for the ARVN…