Riverine Operations
1966 - 1969

Chapter II: 

The Concept of a Riverine Force

In July 1965 the staff of the United States Military Assistance Command, Vietnam (MACV), was drafting the campaign plan for 1966, the purpose of which was to help the government of South Vietnam establish control over the people. The staff concluded that it was possible to secure government control over the I, II, and III Corps Tactical Zones, a conclusion largely based on the presence of American and other Free World Military Assistance Forces in these corps areas. In the IV Corps Tactical Zone, however, where there were no U.S. ground forces to bolster the efforts of the Vietnam armed forces, the staff questioned whether the objective of the campaign plan could be attained. The armed forces of Vietnam were considered capable of maintaining their position in the IV Corps, but not of reducing Communist control over significant portions of the population and terrain in the Mekong Delta. While additional American and other Free World Military Assistance Forces were planned for the other corps areas, none were planned for the IV Corps area. In the opinion of the staff, there could be no substantial progress in the IV Corps Tactical Zone unless U.S. ground forces were introduced.

As a preliminary step in studying the possibility of sending U.S. forces into the delta, Brigadier General William E. DePuy, J-3 (assistant chief of staff for military operations) of the MACV staff, directed his planners to survey the delta for land suitable for basing ground troops. A team dispatched to examine My Tho, Vinh Long, Sa Dec, and Can Tho concluded that all land suitable for large tactical units was either heavily populated or occupied by Republic of Vietnam armed forces. If U.S. units were based in the delta, they would have to share already crowded areas or displace a portion of the population. Since neither of these courses was acceptable, the planning staff then searched for other means of basing troops. Obtaining river sand as fill material and building up an area to accommodate a division base was considered. U.S. Military Assistance Command engineers estimated that with the dredge equipment at hand seventeen and a half dredge-years


would be necessary to fill an area large enough to base a division. Since adequate dredge equipment was not available in Southeast Asia, immediate steps were taken to procure additional dredges from the United States, but these were not expected to arrive until late 1966. Although not entirely satisfied with this solution, the planning staff believed the building of a base area by dredging operations to be a sound choice.

In addition to a land base, other means of operating in the delta were needed, and the planning staff turned to the experience of the French in Indochina for answers. The French had used small landing craft extensively to exploit the net of waterways from land bases. The American staff planned to use not only small craft but also a group of larger landing craft that would house and support a riverine force. These ships, the planners believed, might also be able to move along the coastline and major rivers and serve as mobile bases. It was known that during World War II the Navy had converted LST's (landing ships, tank) into barracks ships, and the planners believed that such ships could provide a base for a brigade force afloat. As the concept of an American river flotilla took form, the planners concluded that the LST barracks ships could be altered to furnish a helicopter flight deck and that barges could be provided on which helicopters would be able to land for maintenance. The ships could also be equipped with weapons for defense.

In their initial survey to find anchorage sites in the delta, the planners of the Military Assistance Command suggested seven that might serve. An LST could resupply the river force by traveling from Vung Tau across a stretch of the South China Sea into the selected anchorage sites on the Mekong and Bassac Rivers.

Captain David F. Welch of the U.S. Navy, who headed the Plans and Requirements Division of J-3, the Operations Directorate, U.S. Military Assistance Command, Vietnam, believed that the afloat force concept merited full study and suggested that a task force be set up under a U.S. Navy commander. He discussed the matter with Rear Admiral Norvell G. Ward, Commander, U.S. Naval Forces, Vietnam, who agreed that the idea had possibilities and that some naval ships could be made available.

In early December of 1965, during the monthly Commander's Meeting of the Military Assistance Command, Vietnam, General DePuy briefed General William C. Westmoreland and his commanders on the concept of a Mekong Delta riverine force that would employ an Army brigade with a comparable Navy organiza-


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tion, and that would operate from various anchorages within the delta. The plan called for the development of two land bases, one for an infantry division headquarters and one brigade, and another for one brigade to be located in the northern part of the delta, probably in Long An Province. A third brigade would be based on the water. With the use of a mobile floating base, the mingling of U.S. troops with the Vietnamese population could be reduced-a prime consideration in view of the reluctance of the Vietnamese to accept U.S. ground forces within the delta. General Westmoreland declared the idea of a floating base "most imaginative," and directed that a team be sent to brief Headquarters, Pacific Command, and solicit its support.

When General Westmoreland had accepted the idea, reconnaissance was conducted to find a land base for a division headquarters and one brigade. General DePuy and Colonel Sidney B. Berry, Jr., Senior Advisor, 7th Division, Army of Vietnam, selected a base site approximately eight kilometers west of the town of My Tho, where the Kinh Xang Canal enters the My Tho branch of the Mekong River. According to French hydrographic maps, adequate sand deposits for fill material existed nearby. A request was then sent to the Joint Chiefs of Staff in Washington for an


additional infantry division to employ in the IV Corps area. For planning purposes the unit was designated Z Division.

During the latter part of December a MACV team headed by  General DePuy met with the Pacific Command staff and outlined a general plan for the riverine force. After a period of discussion, the Pacific Command staff accepted the feasibility of the proposal. I In the discussion the concept that the river force operating within the Mekong Delta would be a joint Army-Navy task force was emphasized. It was felt that barracks ships, then in storage, could be utilized to house part of the force, and that these barracks ships could be supported by small landing craft, patrol boats, and helicopters. Such support would enable the river force to conduct operations within a defined radius of the floating base. In addition, the mobility of the small craft would help to protect the floating base.

Upon acceptance by the Commander in Chief, Pacific, of the feasibility of a riverine force, the Joint Chiefs of Staff tentatively approved the employment of an Army division in the Mekong Delta to put the plan in operation. The force was to be provided barracks ships and LCM-8's. The matter of land bases was left unanswered in the joint staff action of the Commander in Chief, Pacific.

In Washington the Vice Chief of Naval Operations, Admiral Horacio Rivero, Jr., supported the concept of a riverine force and approved a proposal to send a planning group to Saigon to work with the MACV staff. The group was asked to develop a complete plan and to specify the means to support it. Headed by Captain David Bill, U.S. Navy, Office of the Chief of Naval Operations, and consisting of representatives of the Bureau of Ships, the Marine Corps, and the Amphibious Command, Pacific, the planning group arrived in Vietnam in January of 1966. Together the MACV staff and the Navy group studied in detail the experience of the French and Vietnamese with river assault forces in order to establish a similar American force, but one with greater capabilities. Under the leadership of Captain Welsh and Captain Bill, requirements were drawn up for self-propelled barracks ships (APB's), LST's, large covered lighters (YFNB's), large harbor tugs (YTB's), landing craft repair ships (ARL's), and a mine countermeasures support ship (MCS); all were to carry appropriate armament for the area of operations. The LCM-6 would be used instead of the LCM-8, which was in limited supply. 

In a message of 19 February, the Commander in Chief, Pacific,


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 requested that the Commander, U.S. Military Assistance Command, Vietnam, develop and submit a detailed plan of operations and logistical support for the employment of a Mekong Delta Mobile Afloat Force. The plan was to cover force composition and phasing, tasks to be executed, methods of execution, navigable areas, operating areas, afloat force locations, afloat force base, provisions for U.S. Air Force, Navy gunfire, and helicopter support, and command relationships. The Commander in Chief, Pacific, Admiral Ulysses S. Grant Sharp, Jr., also asked for amplification of the logistics involved: depots and ports from which support would be provided, additional facilities required at the logistic support base, requirements for additional lighterage, and specification of other resources needed to support operations. Representatives of Admiral Sharp would meet with the MACV staff to "assist in the development of the foregoing and to facilitate subsequent evaluation and review." The MACV-Navy group continued to plan, following the guidance of the Commander in Chief, Pacific.

The planning culminated in a MACV study, Mekong Delta Mobile Afloat Force Concept and Requirements, dated 7 March 1966, which was forwarded on 15 March 1966 to the Commander in Chief, Pacific, for approval. The study articulated fully for the


 first time the concept for the Army-Navy force afloat. It later proved to be a far-sighted and comprehensive blueprint for the preparation of both Army and Navy components and the conduct of operations. Most of the planned features of the force as stated in this document later materialized in the operational force.

The study recommended that the force contain a U.S. Army reinforced brigade consisting of three infantry battalions, an artillery battalion, and other combat and combat service support. The force would be based aboard U.S. Navy ships that would include 5 self-propelled barracks ships, 2 LST's, 2 large harbor tugs, and 2 landing craft repair ships. In addition, two U.S. Navy river assault groups would provide tactical water mobility. Each assault group would be capable of lifting the combat elements of one reinforced infantry battalion. A small salvage craft would be necessary to recover damaged ships or craft. The reinforced brigade would be organized under the current standard ROAD (Reorganization Objective Army Divisions) tables of organization and equipment, with limited augmentation. Certain equipment specified in the tables, such as tents, mess facilities, 106-mm. recoilless rifles, antitank wire-guided missiles, and all wheeled vehicles except artillery prime movers were to be deleted from the force requirements. The number of 90-mm. recoilless rifles in each rifle company was to be reduced from six to three to improve the mobility of the weapons squads. The 4.2-inch mortars would accompany the force and be moved by water or air to field positions as necessary. Radios would be either ship-mounted or man-portable. Coxswains of plastic assault boats were to he designated in the proposed tables and trained upon arrival in Vietnam. Enough troops from each of the units afloat would be left at a land base to maintain equipment left in storage. The plan provided for an augmentation of three counter-mortar radar sections, each manned by nine men, to operate and maintain ship-mounted counter-mortar radars. A mobile Army surgical hospital team, U.S. Air Force tactical air control parties which included forward air controllers, Vietnam Army liaison troops, and additional ANPRC-25 radios were to be furnished from sources outside the parent division of the brigade.

Each river assault group, later designated river assault squadron, was to consist of the following: 52 LCM-6's to serve as armored troop carriers, 5 LCM-6's to serve as command and communication boats, 10 LCM-6's to serve as monitors, 32 assault support patrol boats, and 2 LCM-6's to serve as refuelers. A salvage force would include: 2 2,000-ton heavy lift craft, 2 YTB's for salvage, 2 LCU's


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(landing craft, utility), and 3 100-ton floating dry docks. The Mobile Afloat Force concept stated the specific tasks the force was to accomplish: secure U.S. base areas and lines of communication required for U.S. operations; conduct offensive operations against Viet Cong forces and base areas that posed a threat both to the national and to the IV Corps Tactical Zone priority areas for rural construction in co-ordination with Republic of Vietnam armed forces and other U.S. forces; isolate the most heavily populated and key food-producing areas from Viet Cong base areas; interdict Viet Cong supply routes; and in co-ordination with the Vietnam armed forces provide reserve and reaction forces in the IV Corps Tactical Zone.

Because the Viet Cong forces were dispersed throughout the Mekong Delta, the river force would be required to operate in many locations. Initial operations would be conducted in the provinces to the north of the Mekong River-Go Cong, Dinh Tuong, Kien Phong, Kien Tuong, and as far north as the Plain of Reeds. (See Map 5.) Once the Viet Cong main force units were neutralized in these areas, with the U.S. Navy GAME WARDEN forces con-


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 trolling Viet Cong cross-river movements, the center of gravity of U.S. operations would shift south into the provinces between the Mekong and the Bassac and eventually south of the Bassac River.

It was decided to use a brigade for initial operations because the experience of U.S. forces in Vietnam indicated that the brigade was the smallest U.S. unit that could be safely and economically kept in the delta. It was large enough to defend its base against heavy enemy attack and at the same time to have forces available for offensive operations.

The formal plan of the Military Assistance Command required the construction of a land base by dredging. Since land reclamation would be expensive and time-consuming, however, the plan also recommended the creation of a water base as well in order to use American forces most effectively. The plan indicated that the land base near My Tho could be made available at the end of 1966 or in early 1967.

Criteria for the selection of anchorages for the floating base were established. The base was to be reasonably near an airfield;


be within or contiguous to a relatively secure area; have access to a land line of communications; have enough room to anchor the entire force; and have a river bank that would permit debarking of artillery to provide fire support to the force. Sites that met most of the above criteria were found in the vicinity of My Tho, Vinh Long, Cao Lanh, Tra Vinh, Can Tho, Long Xuyen, and Dai Ngai, which was in the vicinity of Soc Trang.

Recognizing that the My Tho land base would not be large enough to accommodate a division headquarters until early in 1968, the plan called for the Z Division to go initially to Ba Ria, which lies north of Vung Tau. The division base was to include a division headquarters, a support command, one brigade, and a storage area for the heavy equipment and rolling stock of the two brigades sent into the delta-one to be land-based near My Tho rather than in Long An Province, and a second to be the Army component of the Mobile Afloat Force. Vung Tau was to be the port for staging and resupplying the Mobile Afloat Force. Minimum security measures would be needed for the force when it was at Vung Tau and when it was traveling from there to the Mekong River. During navigation of the major rivers, however, continuous security measures would be necessary. Such movements were to be considered ventures through hostile territory and were to be handled much the same way as running a tactical land convoy.

The plan provided for continuous air cover, both by fixed-wing tactical aircraft and armed helicopters. Advance, flank, and rear security on the rivers was to be provided by U.S. Navy river assault groups. GAME WARDEN forces would provide intelligence to assist in reconnoitering the route. The mine countermeasures were to be chain drags pulled along either side of the channel to cut command detonation wires of river mines, and mine-hunting sonar. Canals terminating in the main river might harbor hostile boats and were therefore to be reconnoitered by both boat and air. Armed helicopters, in conjunction with the Navy assault groups, were to cover the banks of the rivers and search out possible ambush sites. The major ships were to be at a condition of highest watertight integrity during transit, and fixed weapons were to be manned to counter enemy attack. Major ships of the force were to be moved in daylight hours.

At the anchorage of the afloat base, an area security plan would be in effect, with Army security forces on shore and reinforced by artillery. Outposts including foot and boat patrols would be used. The barracks ships would be moored near the center of the river


and their countermortar radars could provide coverage of the surrounding area. All weapons would be manned, with an Army-Navy reaction force standing by while the ships were at anchor.

The plan recognized three principal enemy threats. The first was infiltration by small mortar or recoilless rifle teams, which would attempt to penetrate the infantry perimeter ashore. These teams would probably fire several rounds quickly and then withdraw rapidly. The second threat was that of a large-scale, overt attack. The third and possibly the most critical threat to the floating base would come from the water-floating mines, swimmer saboteurs, and suicide boats. Measures to counter the threats were left to the commanders immediately concerned.

The Mobile Afloat Force concept provided for a variety of tactical operations. The force would remain in an enemy base area as long as operations could be profitably conducted-about four to six weeks. Ground operations would last four to five days, after which troops would be allowed a rest of two or three days to dry out and to repair equipment. It was believed that the force could conduct four operations a month. A brigade would be deployed in the delta for as long as six months, with the possibility of rotation with either the brigade at My Tho or that at Ba Ria. The force would obtain intelligence and develop plans prior to its arrival in a base area, and operations would commence as soon as the floating base arrived at its anchorage. The brigade would rely heavily on local Vietnamese intelligence organizations.

To acquire knowledge of the area in which the force was operating, elements of the brigade, embarked in Navy assault group boats, helicopters, and plastic assault boats, would be employed to gather data on stream and canal depths, height of banks, areas for beaching, possible artillery positions, helicopter landing zones, the local population, and the enemy.

Full-scale operations would be conducted by deploying the force into the combat area by water, land, and air. Security for the floating base would require from a company to as much as a battalion in the immediate base area. Operations could range up to fifty kilometers from the floating base and, in exceptional cases, beyond. Security measures similar to those for relocation of the major ships would be taken for the movement of the assault craft formations during operations. Tactical air and armed helicopters were to fly cover, and artillery would displace by echelon as required to provide continuous fire support. The assault support patrol boats were to furnish forward, flank, and rear security, and to sweep for shore-


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ASSAULT SUPPORT PATROL BOAT. A high-speed armored boat used for waterway interdiction, surveillance, escort, mine-sweeping, and fire support.

 commanded mines. Preparatory fire could be delivered by the armament of the Navy assault groups, by artillery, and by air. Landing of the force would be in accordance with the tactical plan and the armored troop carriers would then withdraw to rendezvous points or return to the afloat base for resupply. At least one armored troop carrier would be designated as a floating aid station located at a prearranged point in the operational area of the battalion that it was supporting. Some elements of the force could deploy by water or air beyond the immediate landing areas to cut off withdrawing enemy troops and some could be held afloat as a reserve. The river force would prevent the enemy from withdrawing across the major rivers. Assault support patrol boats and monitors not required to protect the troop carriers would be used to provide flank and rear security, close-in fire support, and forward command post protection.

Command and control would be exercised through the use of command and communications boats, which were to provide space and communications for battalion and brigade command groups. Command helicopters could also be used to control operations.


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 Helicopters would be used to deploy a portion of the ground force, to position artillery, and to deliver reserves for the purpose of blocking the enemy or exploiting success. Armed helicopters would be employed for escort and fire support. Large Viet Cong forces encountered in these operations were to be neutralized or destroyed by fire and land maneuver. Should no large enemy force be encountered, the Mobile Afloat Force would be redeployed to another area of operations or the area would be systematically searched and enemy resources captured or destroyed. It was estimated that a battalion could conduct an operation throughout an area of forty square kilometers in four to six days. After troops had closed in on the final objective they would be met and withdrawn by the Navy assault group boats or possibly by helicopters. The withdrawal phase was considered critical because of the possibility of ambush and mines. Alternate routes and decoys would be used, but the basic concept for withdrawal would be the same as that of the movement to contact. Mine-clearing devices and air cover would be used. (Diagram 3)

All available means of fire support would be employed by the force, using the air and ground operations system common throughout Vietnam. Sorties would be allocated upon planned requests; emergency requests would be honored in accordance with priorities. The Direct Air Support Center at IV Corps Tactical Zone headquarters in Can Tho would be responsible for the allocation of


Diagram 3 - Riverine Operation and Base Defense.

Diagram 3. Riverine operation and base defense.

 tactical air support with airborne forward air controllers utilized to the maximum. Artillery support would be furnished in the traditional manner, providing fire support to all echelons of the force. Gunfire support would also be supplied by assault support patrol boats and monitors. Army helicopter gunships would be requested and allocated by the division in the same manner as for other divisional brigades.

The Vung Tau Area Support Command would provide common items of supply and logistic support peculiar to the Army; the Navy would furnish items peculiar to the Navy. A small Navy


support facility at Vung Tau would probably be necessary. Two LST's from Vung Tau would take care of all resupply except Class III. Each would be capable of carrying ten days' dry cargo for all elements of the force. One LST would remain on station with the force for seven days as a floating supply point. At the end of the seven days, the LST on station would be relieved by the second ship carrying ten days of supply, and would return to Vung Tau for replenishment.

Self-propelled barracks ships would be stocked with thirty days of frozen and chilled components of Class I and thirty days of dry components prior to deployment. Resupply of Class I would be scheduled to draw on the initial provisioning to a fifteen-day level by the time an APB returned to Vung Tau. The Navy would be responsible for operating all messes aboard ships, utilizing both Army and Navy mess personnel.

Resupply of petroleum products would be accomplished by having the craft of the Navy assault groups refuel from the APB's and the supply LST. The supply LST would refuel the APB's and other ships of the flotilla as required. Gasoline for the assault boats and vehicles would be supplied from two LCM-6 tankers, each with a capacity of 10,000 gallons. The LST would be refilled by commercial barge at ten-day intervals. Fuel for helicopter companies would be provided to the base by commercial contractor. U.S. Army, Vietnam, would supply what the commercial contractors could not.

The LST supply ships would carry that portion of the Class V basic load not carried on the APB's and ATC's. Army Class V carried aboard an APB would be limited to that portion of the basic load carried by the individual soldier and ten days' supply for Army weapons mounted on the ship. A normal allowance would be carried for the Navy weapons. The Army element of the force would prepare loading plans for that portion of the basic load to be carried on the ATC's. An operating allowance of Class V would be carried on the Navy assault group craft for all mounted weapons, with a ten-day resupply for these weapons on the supply ship.

Resupply of forces operating away from the Mobile Afloat Force anchorage would be tailored to the specific operation and would vary with the size of the force, duration of the operation, and distance from the anchorage. Resupply would be accomplished primarily by ATC and helicopter. Airlift and other means of transportation could be called upon to augment the capacity of the organic force for resupply as warranted by the area and nature of


operations. Matériel to be evacuated to Vung Tau or to the division base at Ba Ria would be carried by the resupply ships on their return to Vung Tau. Aircraft would be used for evacuation and for the replacement of urgently needed materiel between supply ship turnarounds. The Army and Navy components would retain maintenance responsibility for organic materiel, including parts supply for service-peculiar items. Each component would provide repair stores and load lists accordingly.

Army responsibility for maintenance would be limited to organizational maintenance of all materiel and direct support maintenance of weapons, vehicles, signal equipment,. and assault boats and motors. Shops on the APB's would be used by unit armorers and maintenance men to perform organizational maintenance. Billeting space for a maintenance detachment of one officer, three warrant officers, and twenty-seven enlisted men, and shop space of approximately 1,500 square feet would be required on the ARL's to meet the Army direct support requirements.

All Navy ships and smaller craft were to arrive in Vietnam in operational condition. Maximum operational time would be available prior to regular overhaul. Two ARL's constituted the major repair arid maintenance assets for the force and would normally remain with the force to function as advanced tenders. ARL shop spaces and equipment would be designed for a broad range of repair and maintenance of all craft and ships of the force and for overhaul of all assault craft. In addition, shop spaces were to be manned by the Army to provide for repair and maintenance of Army equipment.

Medical care would remain a service responsibility aboard ship. The Army would provide medical service for all elements of the force when they were away from the flotilla on an operation. Two medical evacuation helicopters would be stationed at the airfield closest to the area of operations to evacuate patients from battalion aid stations located on ATC's or from the battlefield to a mobile Army surgical hospital or an APB. Further evacuation to hospitals in the Saigon or Vung Tau area would be by helicopter or fixed wing aircraft. Hospitalization would be in the Saigon, Bien Hoa, and Vung Tau areas. A mobile Army surgical hospital located at the land base near My Tho, in conjunction with the brigade to be based there, and a surgical team located on an APB, would provide surgery and medical treatment necessary to prepare critically injured or ill patients for evacuation to hospitals. A helicopter pad, sixteen-bed dispensary, and surgical suites with equipment neces-


nary for one surgical team would be provided on each APB.

Communications would be provided by the permanently installed Army and Navy radio equipment aboard each ship and assault craft. This equipment would provide command, tactical, and logistical communication links to higher and subordinate headquarters. Tactical communications ashore would be by man-packed radios and by airborne relay when required.

General command arrangements had been set forth previously by General Westmoreland. The plan indicated that they would be further developed by study. The command relationships of the force were to be a major topic of discussion for many months after the publication of the Mobile Afloat Force concept.


CONTENTS  -  Chapter 3