Riverine warfare characterized the contest for control of the inland waterways of the Republic of Vietnam (RVN, South Vietnam). The Mekong Delta was the geostrategic center of South Vietnam. With an area of 15,450 square miles and nearly 8 million inhabitants, the Mekong Delta constituted almost one-fourth of the country’s territory and held about half of its population. Even more importantly, the delta was the agricultural production center of the entire region, the rice bowl of Southeast Asia.
The Mekong Delta is a flat alluvial plain created by the Mekong River and its many tributaries. Only one hard-surfaced road, Highway 4, traversed the delta south of Saigon. On the other hand, the region had some 1,500 miles of navigable natural waterways, interconnected by another 2,500 miles of human-made canals of varying width, depth, and condition. It was a perfect area for riverborne operations.
Although virtually no People’s Army of Vietnam (PAVN, North Vietnamese Army) units operated in the Mekong Delta, it was a major Viet Cong (VC) stronghold. In mid-1966 the area held an estimated 28 VC battalions and 69 separate companies, totaling some 82,500 troops. Almost one-third of all VC actions against South Vietnam took place in the delta, and the VC controlled an estimated 24.6 percent of the region’s population. As part of their overall strategy, the VC attempted to cut off the flow of rice from the delta.
The Mekong Delta constituted the Army of the Republic of Vietnam’s (ARVN’s) IV Corps Tactical Zone. Three ARVN divisions— the 7th, 9th, and 21st—were based there. The Republic of Vietnam Navy (VNN, South Vietnamese Navy) also operated 6 river assault groups and 11 coastal groups in the waters in and adjacent to the delta. The South Vietnamese river assault groups were patterned directly after the Dinassauts, operated by the French in the Indochina War.
The American military first entered the Mekong Delta in 1957 when U.S. Navy advisers replaced their French counterparts. By 1966 no American ground units were yet in the delta, but the U.S. Army’s 13th Combat Aviation Brigade provided support to the ARVN. The U.S. Navy had two task forces operating in Mekong Delta waters. Task Force (TF) 115, under Operation MARKET TIME, patrolled the coastal areas to prevent VC infiltration and resupply from the sea. In Operation GAME WARDEN, TF 116, also known as the River Patrol Force, worked the rivers. Operating with a U.S. Navy helicopter attack squadron, SEAL teams, and a minesweeping division, the River Patrol Force conducted reconnaissance patrols, salvage operations, day and night ambushes, and hit-and-run raids.
The concept of a joint U.S. Army–U.S. Navy riverine force for the Mekong Delta emerged from a March 1966 study by the Military Assistance Command, Vietnam (MACV), titled Delta Mobile Afloat Force Concept and Requirements. The missions of the joint riverine force were to secure U.S. base areas and lines of communication, conduct offensive operations against VC forces in the area, isolate the most heavily populated and key food-producing areas from the VC, interdict VC supply routes, and provide reserve and reaction forces for ARVN units operating in the IV Corps Tactical Zone.
One of the principal reasons behind the concept of the Mobile Riverine Force (MRF), as it came to be designated, was the lack of a suitable land base area for a large U.S. ground force in the densely populated Mekong Delta. The MACV plan called for the establishment of a relatively small land base, created by dredging. It would house units of the force’s support structure and equipment that the force would not need while afloat. In June 1966 General William Westmoreland personally selected a site near My Tho for the new base, which was christened Dong Tam.
The planners believed that at least a brigade-sized unit was needed in the Mekong Delta. The original concept called for a force consisting of two river assault groups (later called river assault squadrons), supported by five self-propelled barracks ships. The plan was approved by the Department of Defense on July 5, 1966, but at the same time Secretary of Defense Robert McNamara decided to cut the number of barracks ships from five to two.
As a result of McNamara’s decision, the authorized force had afloat berthing space for only one of a brigade’s three maneuver battalions. The U.S. Navy created space for another battalion by providing a towed barracks barge. The force, however, could still maintain only two battalions afloat. As a result, the brigade habitually operated with only two battalions, while the third battalion secured the land base at Dong Tam.
The U.S. Army element of the MRF was the 2nd Brigade of the 9th Infantry Division. Under its first commander, Colonel William B. Fulton, the 2nd Brigade consisted of the 3rd and 4th battalions, 47th Infantry; the 3rd Battalion, 60th Infantry; and the 3rd Battalion, 39th Artillery, a towed 105-millimeter (mm) unit. The 9th Infantry Division was activated specifically for the Vietnam War at Fort Riley, Kansas, on February 1, 1966.
Its lead elements arrived in Vietnam on December 16, 1966. Initially the division’s 1st and 3rd brigades operated from Bearcat, just south of Saigon and north of the Mekong Delta, in the III Corps Tactical Zone. The 2nd Brigade operated from Dong Tam.
The U.S. Navy component of the MRF was River Assault Flotilla 1, also known as the Riverine Assault Force and TF 117. Initially under the command of Captain Wade C. Wells, TF 117 consisted of the 9th and 11th River Assault squadrons, which were further organized into river assault divisions. A river assault squadron could carry a battalion, and a river assault division could carry a company. By the time the MRF was disbanded, TF 117 had grown to four river assault squadrons, with the addition of the 13th and the 15th River Assault squadrons.
A 400-man river assault squadron was a powerful flotilla. It consisted of up to 3 command-and-communications boats, 5 monitors, 26 armored troop carriers (ATCs), 16 assault support patrol boats, and 1 refueler plus a supporting underwater demolition team, an explosive ordnance detachment, and a riverine survey team.
During the life of the MRF, many local innovations improved the equipment and operating procedures. Perhaps the most important was the mounting of artillery on barges, which greatly increased the mobility—and therefore the operational range—of the brigade’s artillery battalion. Each barge carried two 105-mm howitzers, their crews, and basic loads of ammunition. Field artillery requires stationary firing platforms and fixed aiming points, which meant that the barges had to be beached along a river or canal bank in order to fire effectively. This did, however, allow for direct support fire to ground units once they were landed. Other important innovations included the building of helicopter landing platforms on the ATCs and the use of helicopter landing barges.