The Comanding General II Field Force, Vietnam, exercised operational control of the Army contingent while COMNAVFORV commanded the naval component, designated the Riverine Assault Force (Task Force 117). Commander Task Force 117, also titled Commander River Assault Flotilla One 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 Group Alpha with squadrons 9 and 11, and Mobile Riverine Group Bravo, with squadrons 13 and 15.
Each 400-man squadron, divided further into two river assault divisions, marshalled 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 Army troops. Also installed on the former amphibious landing craft were helicopter landing platforms. A number of craft 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 firepower of these converted landing craft, each squadron was provided with 8 to 16 newly designed assault support patrol boats for minesweeping and escort duties.
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
2 self-propelled barracks ships (APB)
1 LST (another LST operated between the MRF and Vung Tau)
1 specially configured landing craft repair ship (ARL)
1 non-self-propelled barracks craft (APL)
1 repair, berthing, and messing barge (YRBM)
2 large harbor tugs (YTB)
1 net-laying ship (AN)
Mobile Riverine Base Ships
1967-1968
APL 26
Askari (ARL 30)
Benewah (APB 35)
Caroline County (LST 525)
Cohoes (AN 78)
Colleton (APB 36)
Indra (ARL 37)
Kemper County (LST 854)
Mercer (APB 39)
Nueces (APB 40)
Vernon County (LST 1161)
Washtenaw County (LST 1166)
Whitfield County (LST 1169)
Windham County (LST 1170)
Satyr (ARL 23)
Sedgwick County (LST 1123)
YRBM 17
YTB 84
YTB 85
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 operation. The base contained barracks, mess halls, repair shops, floating crane YD 220, a C-130 airstrip, small drydocks, and waterfront facilities for the river craft. Further, the Army based the headquarters of the 2d Brigade, 9th Infantry Division at Dong Tam.
The Navy's first Mobile Riverine Force contingent arrived in South Vietnam on 7 January 1967, when Whitfield County disembarked River Assault Squadron 9 at Vung Tau. This and following units underwent extensive preparation in river warfare at the Naval Inshore Operations Training Center, Mare Island, California, before deployment to Southeast Asia. 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 enemy guerrilla units around Dong Tam. The first major battle occurred between 19 and 21 June when the Army-Navy team trapped three Viet Cong companies about 15 miles south of Saigon and killed 255 enemy soldiers. Another 59 Communists died in the area during July. Reacting to intelligence that two Viet Cong battalions were preparing to attack Dong Tam, the 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 sort 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 afterward.
The Viet Cong, however, eventually adjusted to MRF tactics and struck back. During Operation Coronado V in September 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 vessels in the convoy had been hit by enemy fire, three sailors were dead and 77 were wounded. Another six men were killed or wounded in an ambush later that same month. Still, the MRF, acting in conjunction with the Vietnamese Army 7th Division, trapped elements of the Viet Cong 263d and 514th Main Force Battalions in October and inflicted 173 casualties on these units.
From October to the end of November, the Mobile Riverine Force searched for enemy troops reportedly concentrated north of the Mekong between Sa Dec and Dong Tam, but the enemy avoided significant 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 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 delta's 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 Mobile Riverine Base 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, ten armored troop carriers, three monitors, and one 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 Communists mounted serious post-Tet attacks, the riverine force decimated the Viet Cong 514th Main Force 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 forces.
In July and August, the Mobile Riverine Force ranged throughout the delta with its full complement 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 large- scale penetration of the U Minh Forest, a longtime Viet Cong stronghold. Although the enemy fiercely resisted this intrusion, causing heavy allied casualties, this military presence was maintained. The operation heralded a subsequent campaign to deny the Communists security in any area of the delta. Having demonstrated their worth during two years of combat, Mobile Riverine Force units would be in the vanguard of this new strategic approach to the war.
