The Monitors were the battleships of the Mobile Riverine Force. They were equipped with varied armament including 105mm cannon in turrets, 40mm cannon, or napalm weapons as in this photo. These Zippo Boats were very effective against VC spider holes or other such bunkers and fortifications.
A U.S. Navy Mk I PBR inspects a junk in Vietnam.
The MRF was not a true joint task force with a single commander. According to MACV Planning Directive 12–66 of December 10, 1966, army units of the force came under the commanding general of II Field Force, who exercised operational control through the designated subordinated headquarters, in this case the 9th Infantry Division. Navy units of the force came directly under the operational control of the commander, U.S. Naval Forces in Vietnam. The document stipulated coordination between the army and navy units involved, with the navy providing close support to the army. Although in U.S. practice the doctrinal concept of close support implies that the supported force directs operations, the determination of mission and area of operation of the MRF was a constant source of friction between the army and navy component commanders.
In practice, the target and area of operations usually was selected by the commander of the 2nd Brigade or a higher-echelon army commander. The 2nd Brigade and TF 117 commanders then agreed on the general timing and task organization of the mission. At that point a joint planning staff developed the scheme of maneuver in the target area. From there they worked backwards to work out the details of the assault or landing, the water movement, and the loading phases. Then the final operations plan was briefed to the two commanders, usually aboard the MRF’s flagship, the landing ship Benewah.
The operations of the MRF consisted of coordinated airmobile, ground, and waterborne attacks, supported by air and naval forces. Once the force made contact with the VC, commanders quickly moved to cut off possible escape routes by moving units into blocking positions on the VC flanks and rear. After artillery fire, helicopter gunship fire, and tactical air strikes were directed into the VC positions, ground troops then swept the area. During the MRF’s first year of operations, these tactics proved very effective. The VC often were disoriented and caught by surprise. Prior to the arrival of the MRF in the Mekong Delta, the VC had anticipated attacks primarily coming from the land and air. Their defenses therefore almost always faced away from the water.
Over time the VC learned to deal with the new situation. While under way, the principal security threats to the MRF came from command-detonated mines in the waterway and ambushes along the shore, with heavy fire from recoilless rifles and B-40 rockets. While the MRF was anchored, the most critical threats were from floating mines, swimmer saboteurs, and suicide attack boats. The MRF developed security measures to deal with all of these.
During operations, all troop movements were controlled and coordinated from the joint tactical operations center on the flagship. The army element of the staff normally was supervised by the brigade executive officer. The brigade commander operated with his forward command group from a firebase. During daylight hours they were usually aloft in a command-and-control helicopter. Battalion command posts were divided into forward and rear tactical operations centers. The battalion commander operated from the forward command post aboard the command ship of the river assault squadron. The battalion rear command posts were controlled by the executive officers and located aboard ship at the mobile riverine floating base.
Operating in a riverine environment presented special challenges. Saltwater in the lower reaches of the Mekong Delta caused maintenance problems, often corroding weapons (especially the steel links of belted machine-gun ammunition). Operations had to be planned around such constraints as tides, water depth, water obstructions, bridge clearances, and the suitability of river and canal banks for landing sites.
Wet and marshy terrain also caused immersion foot, dermatophytosis, and other foot problems. These diseases increased at high rates whenever the troops operated on land for more than two continuous days. Soldiers in the Mekong Delta almost never wore socks. Once a soldier got into the water, which was unavoidable, wet socks inside his boots would keep his feet wet that much longer after he got out of the water. It was simply impossible to carry enough dry socks and impractical to stop to change socks every time feet got wet.
The main body of the 2nd Brigade arrived in Vietnam on January 31, 1967. On February 15 the VC attacked an oceangoing freighter on the Long Tao, the main shipping channel between Vung Tau on the coast and Saigon. In reaction to this attack, the 3rd Battalion, 47th Infantry, was ordered to conduct operations in the Rung Sat Special Zone, a tangled area of mangrove swamp at the north-eastern corner of the Mekong Delta. The resulting operation, RIVER RAIDER I, was the first joint operation between U.S. Army and U.S. Navy units that would later form the MRF. The operation lasted from February 16 to March 20, with army units supported by River Assault Division 91 of River Assault Squadron 9.
The 2nd Brigade’s headquarters became operational at Dong Tam on March 10. A month later the first of the river assault divisions moved to Dong Tam and began operations with the 3rd Battalion, 47th Infantry. The MRF became fully operational on June 1, 1967. Between then and March 1968, the MRF conducted a series of wide-ranging riverine and combined airmobile and riverine operations designated CORONADO I–XI.
The navy component of the MRF continued to grow. By the autumn of 1968 it reached its full strength of four river assault squadrons, including 184 river assault craft, 4 barracks ships, 2 barracks barges, 3 repair ships, 2 support ships, and 2 resupply ships as well as various other craft. About the same time, the MRF was reorganized into two Mobile Riverine Groups (MRGs). MRG Alpha had five river assault divisions, and MRG Bravo had three.
In mid-1968 the 9th Infantry Division underwent a major change in its mission. On July 25 the division headquarters relocated from Bearcat to Dong Tam, and the other two brigades also moved into the Mekong Delta. For the first time an entire U.S. infantry division was in the delta. As part of this shift, the 2nd Brigade’s mission changed to an almost exclusive focus on the pacification of Kien Hoa Province. The 2nd Brigade finally received its third maneuver battalion afloat, but the newly restricted area of operations greatly reduced the mobility advantages demonstrated during the wide-ranging operations of the MRF’s first year. MRG Alpha continued to support the 2nd Brigade in Kien Hoa Province, while MRG Bravo carried out operations in the southern delta with units of the 2nd, 3rd, and 4th battalions of the Republic of Vietnam Marine Corps.
In November 1968 MRG Bravo initiated the first of the SEALORDS (Southeast Asia Lake Ocean River Delta Strategy) operations, designed to keep Communist forces away from the rivers and canals in western Long An and Kien Tuong provinces. On February 1, 1969, the 25 river assault craft of River Assault Division 91 were turned over to the VNN. The 9th Infantry Division meanwhile was informed that it was to be the first division withdrawn from Vietnam, with the 2nd Brigade to be the first unit deactivated. As part of the Vietnamization process, TF 117 started turning over the rest of its boats to the VNN. On August 25, 1969, the MRF, and with it River Flotilla 1 and the 2nd Brigade, 9th Division, were deactivated.
On both tactical and operational levels the MRF was one of the success stories of the Vietnam War. While it operated, the MRF effectively wrested control of the northern Mekong Delta from the VC and opened Highway 4 for the first time since 1965, which in turn freed the flow of agricultural products from the delta for both export and domestic use.
One intriguing question remains about the composition of the MRF. By doctrine, the U.S. Marine Corps is organized and trained for amphibious warfare missions. It seems odd then that U.S. Marine Corps units in Vietnam were deployed in the mountainous north of the country and that a brigade of a newly raised U.S. Army division was assigned the amphibious mission that is supposed to be the U.S. Marine Corps’ raison d’être.
References Croizat, Victor. The Brown Water Navy: The River and Coastal War in Indochina and Vietnam, 1940–1972. Dorset, UK: Blandford, 1984. Cutler, Thomas J. Brown Water, Black Berets: Coastal and Riverine Warfare in Vietnam. Annapolis, MD: Naval Institute Press, 1988. Fulton, William B. Riverine Operations, 1966–1969. Washington, DC: Department of the Army, 1973. Sheppard, Don. “Riverine”: A Brown Water Sailor in the Delta, 1967. Novato, CA: Presidio, 1992.
