Fighting in the Mekong Delta presented myriad difficulties. The entire region is covered with swamp, rivers, streams and canals that severely hampered land movement and placed hardships on ground troops assigned to fight there. Roads were almost nonexistent. The little dry land that did exist was often inhabited by the local population. Setting up viable bases, therefore, usually meant encroaching on their territory—not a popular move in the struggle to win hearts and minds. In order to fight effectively in the Delta and provide the infantry with critical field artillery support, the Army had to learn by trial and error and innovate on the fly. How they came up with a viable and efficient solution to the problem they faced in the Delta is an excellent example of the ingenuity of American soldiers and sailors.
The force thrust into the literal quagmire of the Mekong Delta was the Mobile Riverine Force (sometimes referred to as the Riverine Task Force), consisting of the 2nd Brigade of the U.S. Army’s 9th Infantry Division and the U.S. Navy’s River Assault Flotilla 1. This unit employed a combination of naval riverine craft, landing craft and helicopters in its missions against the Viet Cong operating in the area. The support of field artillery was as essential in the Delta as in any other area. In order to provide this support, the assigned units went through a series of experiments and trials, culminating in the creation of specialized riverine artillery batteries. These batteries, their cannons mounted on barges, could be moved readily along the various waterways and positioned wherever needed to support the maneuver units on shore. Once emplaced, the guns provided fast, accurate fire. When the mission was over, the guns were moved to their next firing point. It was an efficient, workable answer.
The Mekong Delta’s environment hindered both the field artillery operations and the infantrymen who had to slog through its swamps and rice paddies. In the Delta, even ground considered dry is only so in a relative sense because the water table is very high. This in turn makes even dry earth soft. Emplacing artillery in soft ground not only makes firing operations difficult for the crew but also can quickly degrade the accuracy of the guns. Cannon batteries are set up for firing by use of a device called an aiming circle. This instrument ensures that all the guns are pointing in exactly the same direction. The direction is expressed in angular measurements of mils, with 6,400 mils equaling a full 360-degree circle. Such precision enables the entire battery to shoot accurately over long distances using one set of firing calculations, normally an efficient procedure.
The Delta conditions reduced this accuracy and efficiency. After firing a few rounds, a 2-ton howitzer would begin to sink into the soft ground, making hash of the careful alignment of the sights. When the artillery was firing at targets thousands of meters away, as they almost always were, even a small movement of the cannon was enough to throw the trajectory of the round dozens or even hundreds of meters off target. At best, that reduced the effect of the fire on the enemy; at worst, it caused rounds to land short, killing and wounding American or ARVN troops.
The shifting also made traversing the gun much more difficult. To maintain precision, gun crews had to make almost constant corrections for accuracy, which slowed down their response to calls for fire from the infantry. And, the limited road network made resupply complicated. The few existing roads had to be shared with troops and were vulnerable to ambush.
There were some places where guns could be set up, but there were not enough to provide the amount of fire support needed. The troops’ first approach to solving this problem was to create firm ground for themselves using an air-transportable firing platform. This was a 22- by 22-foot square table with four adjustable legs. The legs were detachable so that if they became stuck in the muck, the platform could be lifted back off without them and the legs recovered later. The firing platform was flown in by a CH-47 Chinook helicopter and placed wherever needed. A second helicopter then landed an M-102 105mm howitzer with ammunition directly onto the platform. If a CH-54 helicopter was available, it could lift the cannon, some ammunition and the platform all in one trip.
While the air-transportable platform did provide a solution, it was not a perfect one. Although steady enough to enable accurate fire, it was too small to hold the crew’s equipment and all the ammunition needed for extended firing. More important, the crew was essentially sitting on a raised table and exposed to small-arms fire. Gun crews often ringed the platform’s edge with sandbags, but a better solution was needed.
The next innovation was to mount the howitzers on watercraft, making them mobile, less vulnerable to enemy fire and easier to resupply. The first vessel adapted for artillery use was the LCM-6 (landing craft, mechanized). This 56-foot-long, steel-hulled boat was adapted by the 1st Battalion, 7th Artillery to carry M-101A1 105mm towed howitzers in the cargo bay, along with 450 rounds of ammunition. Special bracing was added to absorb the shock of the cannon’s recoil. The LCM could move under its own power to wherever needed, anchor itself to the riverbank and begin firing. The LCM design worked, but it was still not as stable a platform as the cannon required, and getting the gun into action took time in the cramped space of the cargo bay. The bay was too narrow for the gun’s trails to be opened fully, limiting how far the gun could traverse when firing.
The most successful floating artillery platform was a floating barge. It was the brainchild of two officers of the 3rd Battalion, 34th Artillery: Major Daniel Charlton, the battalion operations officer, and Captain John Beiler, the commander of Battery B. They experimented with Navy pontoons to carry howitzers. The first trial used a large pontoon barge, called an Ammi barge, to carry an M-101A1. It worked, but its deep draft hampered movement.
The next experiment was to connect smaller pontoons to create a usable barge with a sufficiently shallow draft. The Navy’s standard pontoon was the P-1, a 7-by-5-foot model that could be connected to other P-1s. The artillery barge consisted of enough pontoons to make a barge 90 feet long and just over 28 feet wide. Armor plating was welded around the edges, and in the middle were living quarters for the gun crews. On each side of these quarters were platforms that held 105mm howitzers, and at each end of the barge was storage space for ammunition. An entire six-gun battery could be carried on three such barges. The rest of the support sections of the battery used the LCM-8 landing craft, a larger cousin of the LCM-6. One LCM towed or pushed the gun barges to their firing points, another carried ammunition and the third was the battery’s command post and fire direction center. A battalion command post with a helicopter landing pad was also created.
Initially the M-101A1 was the howitzer of choice, but it was soon replaced by the lighter M-102, which sat on a baseplate that enabled it to be quickly traversed through the full 6400 mils. This baseplate was welded to the barge for stability. The M-102 had a range of 11,500 meters and a sustained rate of fire of three rounds per minute, after an initial burst of 10 rounds per minute for three minutes.
The barges were pushed to a selected firing point as close as possible to the supported unit. Being as close as possible to the action meant the guns could range the target with the lowest possible firing charge, which increased the life of the gun barrels. It was preferable to find a section of riverbank clear of vegetation so helicopters could land supplies. The barges were moored on the opposite bank from the battle area to keep the resupply helicopters behind the direction of firing. Winches, mooring lines and grappling hooks secured the barge. The equipment used to lay and aim the guns, the aiming stakes or collimators and the aiming circle, were put ashore on the bank.
To defend itself, a gun barge could rely on more than the crew’s rifles and machine guns. Each gun section carried a number of the lethal “beehive” rounds in case of close enemy contact. These anti-personnel projectiles carried thousands of needle-like flechettes that could shred trees, vegetation and human flesh alike. No attack could continue long in the face of repeated salvoes of beehive rounds. When the barges moved as part of a convoy, the howitzers were pointed toward shore, with beehive, white phosphorus and high-explosive rounds at the ready.
Thus armed, the 3-34th Artillery fought in the Mekong Delta. Initially, Battery A used the airborne platforms while Batteries B and C were carried in barges. All the batteries occasionally traveled by road, barge or air as well as using conventional firebases as the situation allowed. The battalion had to move constantly to keep up with the relatively fast-paced infantry operations executed by the 2nd Brigade and the ARVN and South Vietnamese Marine Corps units also in the Mekong Delta.
When the Tet Offensive began in January 1968, the Riverine Force was sent to the My Tho area, where three Viet Cong battalions were trying to capture the provincial capital of Vinh Long. The 3-34th fired 8,158 rounds during the fight to support the infantry. General William Westmoreland later credited the Riverine Force with saving the Delta. After Tet, the 3-34th traveled the various waterways of the Mekong, taking part in numerous fire missions. Occasionally helicopters lifted the howitzers off their barges to be emplaced inland. In September 1968, the batteries suffered three mortar attacks, an ambush and a mine attack.
The air-transportable platforms and artillery barges gave the soldiers fighting in the Mekong Delta the ability to use field artillery against the enemy. Artillery was more responsive and usually more readily available than close air support, and it provided more firepower than the infantry’s mortars or the guns aboard the Navy riverine craft.
Although they have received little attention for it, the artillerymen of the Mobile Riverine Force used their creative ingenuity to invent an entirely new weapons system, adapted to meet the challenging requirements of war in the Mekong Delta. The American and ARVN grunts who suffered and fought there would have been much more hard-pressed if they had not had the support of the 105mm guns of the 3-34th Artillery.
Originally published in the June 2008 issue of Vietnam Magazine. To subscribe, click here.