Mobile Riverine Force In the Vietnam War , the Mobile Riverine Force ( MRF ) ( after May 1967 ) , initially designated Mekong Delta Mobile Afloat Force , and later euphemistically the Riverines , were a joint US Army and US Navy force that comprised a substantial part of the Brown Water Navy . It was modeled after lessons learned by the French experience in the First Indochina War and had the task of both transport ( of soldiers and equipment ) and combat . The primary base was at Dong Tam , with a floating base at the base of the Mekong River . It played a key role in the Tet offensive . Concept of operations . The Mekong Delta Mobile Afloat Force was originally conceived as providing an all weather " strike " capability in the Mekong Delta , to actively prosecute contact with Viet Cong units in the Vietnam War . A " strike " force was inherently and essentially different from the existing Navy interdiction and patrol forces ( the River Patrol Boats of Operation Game Warden , and the coastal blockade of Operation Market Time ) . The Delta presented a classic venue appropriate to riverine operations such as had not been seen since the Union Navy in the ( American Civil War ) Mississippi Delta , and Sino - American operations in World War II . The Delta had a dearth of reliable roadways , all with predictable choke points at bridges , a literal myriad of creeks , streams , rivers , and canals , frequent monsoon conditions restricting air operations , and ground conditions that were often muddy . Historical experience . A wide range of riverine craft were used by the allies , both before , and during the formalization of the US Navy Brown Water Navy , in 1964 – 1965 . Foremost were the surplus World War II US naval crafts ; LCM s , LCVP s , LSM s , PGMs , LSSLs , etc . , as well as post - war " Nasty " class MTB s . One of the most popular riverine craft was the all - steel LCM which converted nicely into a naval monitor , and was used by the French during the first Indochina war ; and later by the US and South Vietnamese Navies . However , The French , during their war in Vietnam ( 1945 – 1954 ) , had been heavily inspired by the US Navy LCVP , which they had received from the US , as part of the United States massive assistance program to fight communism ( US Forces were fighting in Korea , at that time , and could only give material aid ) . The French took the LCVP design and created an all new , and as it turned out , the only " original " or entirely new boat built for riverine warfare during the French Indochina war ; the STCAN ( a corruption of the acronym STCN , which stood for the French equivalent of the US Navy ' s BuShips , which read Service Technique de Construction Navale ) . The French STCAN was built of steel , approximately long , " V " hulled , with a shiplike bow , was armed with one . 50 cal machine gun , three . 30 cal machine guns , and eight crewmen . Creation of the Mobile Afloat Force . The Mekong Delta Mobile Afloat Force concept paired newly created assault boat units with a brigade of Army infantry . The force contained 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 ( landing craft , utility ) , and 3 100 - ton floating dry docks . Navy boats . It was the French STCAN which , in 1965 inspired the construction of the only US Navy riverine boat which was specifically built for the Vietnam War ; the ASPB Assault Support Patrol Boat . Unlike the US Navy PCF Patrol Craft Fast ( aluminum , also known as " swift boats " ) and PBR Patrol Boat River ( fiberglass , nicknamed " plastics " ) , the Assault Support Patrol Boat was designed and built specifically for Vietnam . They were already baptized in blood on September 30 , 1967 , despite having arrived in Vietnam only 10 days earlier , on September 20 , 1967 . The ASPB , better known as the " Alpha " boat , was approximately long , its hull was constructed of 7 / 32 inch steel , from the gunwale 2 " up it was 1 / 8 inch steel , its superstructure was 1 / 4 inch aluminum . It was armed with two Mk 48 turrets with either 20 mm or . 50 cal machine guns , two single 7 . 62 mm machine guns , one 81 mm mortar , a dragging chain for mine sweeping the river , and had a complement of five crewmen . The boat itself was built especially strong to resist the explosion of mines ; consequently , the " Alpha " boat is mainly remembered for its riverine mine - sweeping duties . Navy Assault Squadrons . Originally two , and ultimately four Navy Assault Squadrons were created : River Assault Squadrons 9 , 11 , 13 , and 15 . The 2nd Brigade of the U . S . 9th Infantry Division was assigned to work with these units . A fixed land base was created by dredging a portion of the Song Ham Luong near My Tho , and was named " Dong Tam . " This became the administrative headquarters of the MRF . Nonetheless , the Navy created a floating Mobile Riverine Base ( MRB ) by assigning barracks ships , and barrage barges ( non - self propelled ) to house both Army and Navy personnel , provide communications and staff support , mooring and support facilities on Ammi pontoons alongside , and refit , rearm , and resupply stores . The MRB also included repair ships ( ARLs ) , and supply ships ( LSTs - Landing Ship Tanks ) . The ships of the MRB also had helicopter landing capabilities , and provided air resupply and medical air evacuation ( " dust off " ) capability , and had significant medical care facilities aboard . Thus , the entire force could move throughout the major rivers of the Delta , and launch troops , on boats , into assault operations deep into the narrowest rivulets and canals . Given the low limit speed of perhaps 6 knots ( or less if opposing the fierce lower Delta currents ) , this " MOBILE " capability made boat assault operations in the furthest reaches of the Delta feasible . Eventually , the MRF included Army floating artillery and mortar barges , which could be moved throughout the Delta and positioned to support the planned area of each assault operation . Integral air support came from newly created Navy gunship helicopter squadron HAL 3 ( Helicopter Attack , Light ) , the SEAWOLVES , based at Dong Tam . This was additional to such air support , both troop insertion and gunfire ships , as the Army tasked to each operation , and air support from Air Force TAC air units on call .