Riverine Assault Force (Vietnam)



While the object of Game Warden was to reduce the enemy’s logistic support, that of the joint Army-Navy Mobile Riverine Force was to locate, encircle, and destroy communist units in Battle. American military leaders patterned the MRF after the French naval assault divisions, or Dinosauts, which performed well in the Indochina War from 1946-1954. The Americans designed a formation especially suited to the Mekong Delta, where the absence assault1of dry land and abundance of navigable waterways made it desirable to station ground troops on board a mobile afloat base. In addition to transporting infantry and artillery, the naval component was intended to provide gunfire support for land sweeps from heavily armed and armored river craft. As finally organized, the Mobile Riverine Force consisted of an Army element, the 2nd Brigade of the 9th Infantry Division. Augmented in mid-1968 by the 3rd Brigade, and a Navy element. The MRF was under COMUSMACV’s overall direction.

The Commanding General II Field Force, Vietnam, exercised operational control of the Army contingent while COMNAVFORV commanded the naval component, designated the River Assault Force (Task Force 117). Commander Task Force 117, also titled Commander River Assault Flotilla 1 for purposes of supply and administration, directed the operations of River Assault Squadrons 9 and 11 (also assigned task group numerical designations). After June 1968 Squadrons 13 and 15 joined the force. That same month the task force was reorganized into Mobile Riverine Force Squadrons 9 and 11 in Mobile Riverine Group Alpha, and Squadrons 13 and 15 in Mobile Riverine Group Bravo.

Each 400-man squadron divided further into two river assault divisions, and marshaled a powerful fleet of five monitors, each monitor was protected with armor and equipped with 50-caliber, 40-millimeter, and 20-millimeter gun mounts, two 40-millimeter grenade launchers, and an 81-millimeter mortar. Another two or three similarly armed and armored craft served as command and control boats. A total of 26 armored troop carriers that mounted .50 caliber machine guns, rapid fire grenade launchers, and 20-millimeter cannon transported the Riverine Infantry. Also installed on the former amphibious landing craft were mounted flame throwers or water cannon to destroy enemy bunkers. A modified armored troop carrier functioned as a refueler for the river force. Beginning in September 1967, to augment the fire power of these converted landing craft, each squadron was provided with 8 to 16 newly designed assault support patrol boats (ASPBs,) for minesweeping and escort duty. The ASPB’s twin 12 cylinder diesel engines gave this boat about twice the speed of the other riverine craft. The added power and maneuverability of this craft made it an excellent boat for providing covering fire.


In addition to leading the naval combat flotilla, Commander Task Force 117 also functioned as commander River Support Squadron 7. He was responsible for the Mobile Riverine Base from which normally one or two infantry battalions and one river assault squadron operated.

Mobile Riverine Base Composition

4 self propelled barracks ships (APB)
1 LST (another operated between the MRB and Vung Tau)
5 specially configured landing craft repair ships (ARL)
1 non-self propelled barracks craft (APL)
2 large harbor tugs (YTB)
1 net laying ship (AN)
Mobile Riverine Base Ships 1967-68

Mobile Riverine Base Ships 1967-68




Benewah (APB-35)Satyr (ARL-23)Cohoes (AN-78)
Colleton (APB-36)Sphinx (ARL-24)
Mercer (APB-39)Askari (ARL-30)
Nueces (APB-40)Indra (ARL-37)
Krishna (ARL-38)




APL-26YRBM-17Winnemucca (YTB-785)
Kalispell (YTB-784)


Caroline County (LST-525)Kemper County (LST-854)Sedgwick County (LST-1123)
Tom Green County (LST-1159)Vernon County (LST-1161)Washoe County (LST-1165)
Washtenaw County (LST-1166)Westchester County (LST-1167)Whitfield County (LST-1169)
Windham County (LST-1170)

The above LST’s rotated with the MRF. There were other supporting LST’s but these were the most frequent.


Mobile Riverine Force units rotated between the afloat base and Dong Tam, a logistic complex three miles west of My Tho that Army Engineers and Navy Seabees built especially for the joint operations. The base contained barracks, mess halls, repair shops, floating crane (YD-220), a C-130 airstrip, small dry dock’s, and waterfront facilities for the river craft. Further, the Army based the headquarters of the 2nd Brigade, 9th Infantry Division at Dong Tam.

The Navy’s first Mobile Riverine Force contingent arrived in Vietnam on 7 January 1967, when Whitfield County (LST-1169) disembarked River Assault Squadron 9 at Vung Tau. This and following units underwent extensive preparations in river warfare at the Naval Inshore Operational Training Center, Mare Island, CA, before deployment to Vietnam. On 28 February COMNAVFORV activated Task Force 117 under Captain Wade C. Wells. In March River Assault Squadron 11 joined River Assault Squadron 9 at Vung Tau. By June 1967, support ship Kemper County, barracks ships Benewah and Colleton and other vessels had arrived in-country to round out the Navy’s MRF Contingent.

MRF units had already fought minor actions against the Viet Cong in the Rung Sat and in the vicinity of Dong Tam. On 1 June, with the MRF up to strength and most units acclimated to the combat area, the force began intensive operations to find and destroy the enemy units around Dong Tam. The first major battle occurred between 19 and 21 June when the Army and Navy team trapped three Viet Cong companies about 15 miles south of Saigon and killed 255 enemy soldiers. Another 59 communist died in the area during July. Reacting to intelligence that two Viet Cong Battalions were preparing to attack Dong Tam, Mobile Riverine Base ships weighed anchor and steamed 61 miles upriver to a new site. There they joined with Vietnamese Marine, Vietnamese Army, and U.S. Army battalions in decimating and scattering the prospective enemy assault force. The MRF recorded success of another in September when a landing and sweep maneuver in the eastern Rung Sat uncovered a cache of 105 rifles and machine guns, 165 grenades, 60 howitzer and mortar shells, and 56,000 rounds of small arms ammunition. A small enemy hospital and 850 pounds of medicine were found soon after.

The Viet Cong, however eventually adjusted to MRF tactics and struck back. Forcing operation Coronado V in September of 1967, the enemy sprang an ambush along a two mile stretch of the Ba Rai River southwest of Saigon. By the end of the four hour engagement half of the boats in the convoy had been hit by enemy fire. Three sailors were dead and 77 wounded. Another six men were killed or wounded in an ambush later that same month. Still, the MRF acting in conjunction with the 7th Infantry Division of the Vietnamese Army, trapped elements of the Viet Cong 263rd and 514th Main Force Battalions in October and inflicted 173 casualties on these Units.

From October to the end of November, the MRF searched for enemy troops reportedly concentrated north of the Mekong between Sa Dec and Dong Tam, but the enemy avoided contact. Then, on 4 December the Viet Cong triggered an ambush against River Assault Division 112 on the Ruong Canal northeast of Sa Dec. The river sailors turned the tables when they fought through the ambush and landed troops on the enemy’s flank. Soon other American and Vietnamese combat units surrounded and killed 266 Viet Cong and captured 321 small arms and 5,000 rounds of ammunition.

MRF actions during the 1968 Tet offensive were the key to the allied military success in the delta and earned the force the Presidential Unit Citation, exploiting the inherent mobility and firepower of the riverine command. COMUSMACV used it as his primary reaction force in the vast delta. During the first week of February 1968, the MRF battled through the streets of My Tho to help recapture the overrun city, and then shifted to Vinh Long for several days of intense combat with three Viet Cong battalions. For the rest of the month the Army-Navy team fought around the deltas chief city, Can Tho. The force killed 544 of the enemy in this period of almost constant crisis.

During the first three months of 1968, the MRB traveled almost 1,000 kilometers while conducting operations in Dinh Tuong Province and entering new areas in Vinh Long and Phong Dinh Provinces. In March, 10 armored troop carriers, 3 monitors, and 1 command and control boat of River Assault Division 112 deployed to I corps and supported allied ground troops with gunfire on the vital Cua Viet and Perfume Rivers.

During the second quarter of the year when the communist mounted serious post-Tet attacks, the riverine force decimated the Viet Cong 514th Main Battalion near Cai lay in the delta and another formation south of Saigon. Fighting to relieve pressure on the capital, the MRF inflicted 687 casualties on besieging enemy troops.

In July and August, the MRF ranged throughout the delta with it’s full compliment of river craft, support ships, and 9th Division troops. In the latter month, the MRF joined with other Army and Navy units and with Vietnamese forces in a longtime penetration of the U Minh Forest, a long time Viet Cong stronghold. Although the enemy fiercely resisted this intrusion causing heavy allied casualties, their military presence was maintained. The operation heralded a subsequent campaign to deny the communist security in any area of the delta. Having demonstrated their worth during two years of combat, the Mobile Riverine Force units would be in the vanguard of this new strategic approach to the war.