From Blue to Green and Brown

Proving its adaptability during the Vietnam War, the U.S. Navy created Coastal and Riverine Forces from scratch that reduced communist infiltration from the sea secured vital waterways, and pushed enemy forces into the hinterlands of the Mekong Delta.

On the morning of 3 March 1965, a UH-1B helicopter piloted by an Army Lieutenant lifted off the pad at Qui Nhon on the central coast of South Vietnam and headed south. On his right, the Lieutenant could see the mountains of the Chaine Annamatique, their steep slopes covered with dark green carpets of jungle foliage, their feet immersed in the blue of the South China Sea. Just before 1030, the pilot rounded the promontory that flanked the northern side of a picturesque bay known as Vung Ro.

Because they sometimes fly in tight formations, Army helicopter pilots have a finely tuned sense of relative motion, and as he surveyed the sapphire waters of the bay below, the lieutenant sensed that something was not right. Focusing on a small, vegetation-covered island he suddenly realized that it was moving!

Swooping down for a closer look, he saw that the "island" was actually a trawler whose decks and superstructure had been camouflaged with potted trees. The pilot reported his discovery, and what would enter the history books as "the Vung Ro Incident" was underway.

What this Army lieutenant did not realize at the time was that he had triggered a sequence of events that would take elements of the U.S. Navy away from their traditional blue-water realm and send them into the green and brown waters of South Vietnam.

Sea Change
A combination of U.S. air strikes and attacks by Vietnamese Navy (VNN) vessels disabled and eventually captured the intruding ship at Vung Ro. On board were large amounts of ammunition and other supplies - many bearing labels from an assortment of communist countries - as well as numerous documents and objects that made it clear the trawler had come from North Vietnam. The long-running debate about whether the North was using the sea to supply communist forces in the South was over.

But there was also concern that VNN forces had taken nearly five days to capture the ship, and U.S. Navy advisers who participated in the operation reported many significant problems with the effectiveness of their South Vietnamese counterparts. U.S. planners concluded that this now-proven threat needed to be countered by an active American effort that would transform the U.S. Navy's in-country role from nominally advisory to openly operational. This was a momentous change that would eventually bring nearly 2 million U.S. sailors and Coast Guardsmen to serve in-country over the course of the war.

The sailors who left gray decks to serve in-country traded their white hats and combination covers for black berets and helmets, their bell bottoms, and khakis for green utilities and various forms of camouflage. Five-inch guns were replaced by machine guns and grenade launchers, rudders and screws gave way to Jacuzzi pumps, and malaria and dysentery joined mal de mer as common afflictions.

Leaving traditional career paths to serve in Vietnam sometimes proved less than career-enhancing, and in-country life lacked some of the creature comforts found in the blue-water Navy, but there have always been "swashbucklers" in the service willing to trade a swab or a typewriter for a .50-caliber machine gun, so there were many volunteers. The preferred ratings for these operations were those with applicable skills, such as boatswains, gunner's mates, and enginemen, but many other ratings were represented, with eagerness making up for the lack of vocational skills.

Market Time
The transition from advisory roles to operational ones began with the creation of the Coastal Surveillance Force, designated as Task Force (TF) 115, whose primary mission - code-named Operation Market Time - was to interdict the flow of supplies to communist forces by conducting random searches among the throngs of junks and sampans that travelled these waters on a daily basis.

Seventeen existing 82-foot patrol boats (WPBs) were provided by the Coast Guard, but for these shallow-water operations, the Navy had to rely on modifying a 50-foot aluminum craft that was being used in the Gulf of Mexico to transport crews to and from offshore drilling rigs. Officially designated as PCFs (patrol craft, fast), these converts were suitably armed with machine guns and naval mortars. Capable of 28 knots, they came to be known as "Swift Boats."

Patrols were marked by extreme contrasts. A Market Time sailor typically spent weeks roasting in the Southeast Asian sun, then found himself battling pounding seas and torrential rains during the monsoon season. While stopping and searching vessels could earn him appreciative smiles from people who understood why he was there, he more often saw the scowls of fisherman and farmers who resented the delay in getting their products to market. Although he was there to help the South Vietnamese people, he could never fully trust them, which meant that despite the tedium of his mission, he could never let his guard down.

Mostly the U.S. sailors' mission was one of deterrence - like the cop on a beat - and it could be frustrating as well as boring. Occasionally a North Vietnamese trawler attempted a run into the shore, offering the opportunity to target a clearly hostile vessel, but these were relatively rare. The business of routine searching for contraband was sometimes interrupted by delivering fire support to friendly units on shore, conducting occasional search-and-rescue missions to recover downed aviators, or providing assistance to vessels in distress.

These sailors were most vulnerable when their craft was tied up at bases ashore. The threat of attack was a constant for virtually all Americans serving in South Vietnam. They never knew when rockets or mortars might rain down, or when a sniper's bullet or a sapper's explosive might send them home early in a zippered bag.

The task at hand was enormous by any calculus. Different sources estimated the daily coastal traffic of South Vietnam ranged from 4,000 to 60,000 vessels - the discrepancy of these figures telling much about the difficulties of the mission. Measuring success was challenging since the only measurable data consisted of successful intercepts and captures, whereas the number of "misses" was entirely unknown. But postwar studies suggest that TF 115 succeeded in extensively altering the enemy's logistics, substantially reducing his ability to resupply guerrilla units by sea infiltration and forcing him to rely instead on much less efficient overland supply through Laos and Cambodia.

Game Warden
The most serious infiltration by land occurred in the southernmost part of South Vietnam, in the region known as the Mekong Delta. Geographically this area represented only one-quarter of the country's land area, but demographically it comprised about half of the population. It consisted of a vast network of waterways, with a spider's web of streams and canals interconnecting four main branches of the Mekong River.

Adjacent to the Delta was the Rung Sat Special Zone (also known as the "Forest of Assassins"), a foreboding maze of waterways, swamps, mangrove tangles, and islands that the communist insurgents, or Viet Cong, had inherited from the bandits and pirates who had long dominated the region. Between the Delta and the Rung Sat was the meandering Long Tau River that provided the capital city of Saigon access to the sea.

Despite the Mekong Delta's long-standing reputation as one of the great "rice bowls" of Asia, the Viet Cong controlled much of the flow of rice to South Vietnamese markets, and the VNN was having difficulty keeping the shipping channels to Saigon open, which hampered needed commercial trade. Consequently, the U.S. Navy was called on to fix these problems, and another task force (TF 116) was created, officially called the River Patrol Force.

Once again, the Navy's blue-water parochialism left it unprepared for this new campaign, known as Operation Game Warden. The needed vessels had to be created by modifying an existing 31-foot fiberglass recreational craft. Designated PBRs (Patrol Boats, River) these crafts were powered by a pair of diesel engines designed for a maximum speed of 30 knots (not quite realized after weapons and ammunition were added). A pair of rotatable, stern-mounted jet pumps manufactured by Jacuzzi Brothers served as both propulsion and steering, obviating the need for screws and rudders. That made them less vulnerable to the vegetation and debris that proliferated in the rivers and canals. A pair of .50-caliber machine guns were mounted forward in an open mount, and a single .50-caliber was mounted aft on a centerline pedestal and often accompanied by grenade launchers or 7.62-mm M-60 machine guns on each side.

In February 1966, Game Warden officially commenced. FT 116's missions were to interdict enemy infiltration, enforce curfews, prevent taxation of water traffic by the Viet Cong, and keep the main shipping channel into Saigon open.

Seven operating bases were set up in both the Delta and Rung Sat and were supplemented by four old LSTs (landing ships, tank) that were brought out of mothballs to be fitted as mobile floating bases. A minesweeping contingent was added that consisted of 57-foot wooden MSBs (minesweeping boats) and regularly patrolled the meandering Long Tau. "Sea Wolf" helicopters (Army hand-me-down UH-1 "Hueys" flown by Navy crews) were added and later supplemented by "Black Ponies" (Army OV-10 Bronco turboprop aircraft also flown by Navy pilots) to provide air support.

The established fleet doctrine was of little use, so these brown-water sailors had to "write the book" as they went. While trial and error are rarely preferable to reliance on established procedures (because of the "error" part, which can be costly), these neophytes learned quickly and enjoyed the autonomy and flexibility that Americans often prefer at the tactical level.

Tactics evolved that included the pairing of PBRs for most operations, with a "Patrol Officer" (a Junior Officer or Senior Petty Officer) in charge of both boats. This allowed mutual support and permitted one boat to conduct inspections while the other "hovered" nearby watching for other dangers (such as ambushes from ashore). Searches were conducted as near as possible to midstream, with one PBR maintaining clear lines of fire to both banks, while the other conducted the inspection with weapons ready, engines running, and the inspected vessels brought alongside but never moored to the inspecting PBR. (Virtually all of these procedures were violated in the famous movie Apocalypse Now, as a single PBR moors to a sampan, shuts down its engines, and ultimately fails to employ weapons discipline.)

In addition to search operations, PBRs conducted nighttime ambushes, aided units under attack on shore, and supported a number of SEAL counterguerrilla operations. Tactical innovations included such things as "acoustical detection devices" (Coke cans filled with pebbles strung across a canal at night), an M-60 machine gun mounted on top of the boat's canopy (to allow firing over elevated canal banks when the tide was low), and a "flamethrower" (a hunter's bow used to shoot flaming arrows).

The enemy too developed his own tactics by taking advantage of low tides to restrict the maneuverable battle space for the PBRs, faking a medical emergency on one sampan to distract U.S. sailors from countering the movements of another, and timing ambushes to occur when the Americans were returning from a long patrol and consequently fatigued.

The early frequency of ambushes by the enemy served as credible evidence that these operations were having the desired effects. Eventually, the Viet Cong were driven from the major waterways. Gone were the VC tax-collecting stations; shipping flowed through the Long Tau, and enemy contact gradually fell off until tedium replaced terror as a major morale problem.

Mobile Riverine Force
Even though Game Warden operations were solving problems on the major waterways, the land areas of the Delta remained in jeopardy. Well-ensconced enemy forces operated with too much freedom in this vital geographic area, and sending in ground forces seemed the logical solution. But the U.S. Army traveled largely on wheels and treads, and there were few roads in this region. With waterways as the highways, some sort of amphibious capability was required. The U.S. Marines would have been the logical choice, but by this time they were fully occupied in "I Corps," the northernmost quarter of South Vietnam.

The solution was to designate yet another Navy task force (TF 117) - dubbed the Riverine Assault Force - that would be combined with the Army's 2nd Brigade of the 9th Infantry Division to form the Mobile Riverine Force (MRF). Mobility was provided by a large fleet of existing landing craft that were converted into various configurations and clustered around a flotilla of larger vessels, including several LSTs that were resurrected and reconfigured for the new purpose. This "jungle green" flotilla could move about the main rivers, positioning themselves where needed to root out enemy concentrations. The soldiers lived in barracks ships during transits, then embarked in modified LCM-6s (landing craft, mechanized) for assault operations.

The LCM-6s had been significantly modified for the various needs of the assault force. The most numerous were the armored troop carriers (ATCs), also known as "Tango Boats." Of the various conversions, this 56-foot craft looked most like the original landing craft, retaining the large bow doors that could be lowered onto the river or canal banks to allow rapid egress of embarked troops. They were heavily armed with an array of machine guns and grenade launchers and one 20-mm cannon. Bar armor pre-detonated enemy recoilless-rifle rounds and rocket-propelled grenades before they could penetrate the troop-filled well deck. A canvas awning over the top of the well deck protected the soldiers from the sun and light grenades. With a seven-man crew, one ATC could transport and land an Army platoon (approximately 40 men) and provide close-in fire support. The craft carried spare ammunition, food, and other supplies for the initial assault and could ferry more during extended operations.

Some ATCs were modified to accommodate a steel flight deck, in place of the canvas awning, where helicopters could actually land to evacuate wounded or perform other support duties, making them the world's smallest aircraft carriers. Others, equipped with medical-aid stations, served as diminutive hospital ships, and still others with large fuel bladders functioned as counterparts to the fleet oiler.

The most formidable craft were the monitors, which functioned as the battleships of the flotilla. Although they too were once LCM-6s, their bow doors had been removed and replaced by a rounded bow. A cluster of weapons similar to those of the ATCs was complemented by a potent 81-mm naval mortar amidships and a 40-mm cannon in a forward turret. Later versions came to Vietnam with 105-mm howitzers replacing the forward cannon. Some monitors were also equipped with flamethrowers (useful for burning away heavy vegetation as well as terrorizing enemy soldiers) and dubbed "Zippos" in recognition of the cigarette lighter that many GIs carried in those days.

The CCB (command communications boat) was similar to the monitor but carried a command-and-control console amidships in place of the mortar. These functioned as a kind of flagship, their banks of HF, VHF, and UHF radios providing commanders the means to coordinate operations.

In late 1967, assault patrol support boats (ASPB) were added to the force. The only riverine craft built from scratch for service in Vietnam, they were designed to function as a hybrid destroyer-minesweeper. At 50 feet and 28 tons, these relative latecomers were crewed by seven sailors and could provide a lot of firepower from an array of machine guns and grenade launchers as well as a stern-mounted mortar and a bow-mounted 20-mm cannon. Their reinforced hulls and chain-drag mine-countermeasures rig could clear the way for an assault, and an innovative underwater exhaust system significantly reduced engine noise (but created maintenance headaches because of their complexity).

Tactics evolved as experience begat innovation. Troops began carrying lines with snap-hooks to aid in water crossing and detonating booby traps; truck tires and sandbags were placed beneath mortar baseplates to absorb the shock of firing; underwear was left behind in the barracks ships because it did not dry as rapidly as fatigues.

Periodically shifting its location, the Mobile Riverine Force anchored in various rivers and conducted a wide variety of operations in both the Delta and the Rung Sat that varied in size and complexity, many large enough to warrant special operational names such as Great Bend, Concordia, and Hop Tac.

In the early hours of the Tet Offensive in early 1968, the MRF moved around the Delta, engaging enemy forces in a series of intense battles. One took place along a three-mile stretch of the Rach Ruong tributary, where the waterway narrowed to a mere 30 yards wide. Enemy forces opened up with heavy machine guns, rockets, and recoilless-rifles, and the prepared Americans retaliated with a heavy barrage, using leveled howitzers to fire deadly "Beehive" antipersonnel rounds with devastating effect, begging comparisons to broadsides exchanged in close-quarters battles during the Age of Sail. The half-hour battle left a large number of enemy dead along the banks as the MRF forces continued down the waterway to their next engagement, a 21-hour pitched battle at My Tho.

In the weeks that followed, the soldiers and sailors of the MRF fought with little rest to preserve South Vietnam's vital "rice bowl," moving around the Delta, driving enemy forces out of and away from the critical cities, inflicting heavy casualties on the Viet Cong, who had at last come out of the proverbial woodwork and into the crosshairs of American guns.

The MRF continued operations after the Tet Offensive and, as time went on, the enemy ceded control of much of the Delta territory. But it was also clear that he was not defeated. Withdrawing deeper inland and relying on the smaller waterways in those areas, he continued to infiltrate from the nearby Cambodian sanctuary that had been allowed as a result of American concerns about widening the war.

SEALORDS
When Vice Admiral Elmo R. Zumwalt Jr. arrived in South Vietnam in the fall of 1968 to take command of the in-country naval forces, he found that the three task forces had successfully carried out their missions. But he also faced two problems that begged solutions. One was the existence of the Cambodian sanctuary, and the other was that morale was suffering because declining contact with the enemy meant that patrols were becoming mind-numbingly routine. The old strategic concept of a "fleet in being" has always suffered from this problem - existence playing an important strategic role, but inactivity breeding discontent.

It was clear that it was time for a strategic adjustment, and Zumwalt responded by creating a whole new task force - TF 194 - and dubbed it SEALORDS, for Southeast Asia Lake, Ocean, River, and Delta Strategy. The idea behind this new strategy was to carry the fight to the enemy by restructuring the forces available and redefining their missions.

Swift Boats were drawn from the coasts to operate in the rivers and canals, PBRs were tasked with deeper penetrations into the smaller waterways, and various elements of the MRF were reassigned to support new penetrating and blocking missions. These newly configured forces probed deeper into the Delta hinterlands to interdict enemy movements, but more important, they were tasked with establishing a barrier near the Cambodian border to cauterize the arterial bleeding that had been suffered as a result of the existing sanctuary.

Initially, this new force conducted four aggressive campaigns - Operations Search Turn, Foul Deck, Giant Slingshot, and Barrier Reef - that established an effective barrier and greatly reduced the amount of infiltration.

Engagements were so common during the Giant Slingshot operation that an acronymic shorthand was developed to speed up the reporting process: ENIFFs were enemy-initiated firefights, FRIFFs were friendly-initiated firefights, while an ENENG represented contact with the enemy in which fire had been initiated by him but not returned, and a FRENG was the converse.

ENIFFS along the Vam Co Dong were so frequent that a particular stretch of the river was called "Blood Alley." In a strange but logical twist, friendly casualties increased significantly, but so did morale among those who preferred the adrenaline-fed activity to the tedium of routine patrols.

Subsequent operations with different names but similar purposes increased the pressure on the enemy and neutralized his effectiveness in various parts of the Delta. New tactics were developed that included the employment of "waterborne guard posts" - a euphemism for ambushes - and the use of giant pontoons to establish small "advanced tactical base camps" (ATSB) in remote waterways. These were eventually extrapolated into larger, more permanent, floating bases designed to maintain control of regions previously belonging to the enemy.

The Americans and their South Vietnamese allies conducted "randomized pressure" operations in the area that took various forms, including organized sorties, emergency response operations, and routine patrols. Early resistance diminished, and gradually local villagers began to provide warnings of enemy movements and plans. It was clear that Zumwalt's strategy was succeeding.

Vietnamization and Postscript
While Zumwalt's aggressive approach injected new life into the U.S. Navy's in-country operations, the progress was made less relevant by a major change in American policy. The unpopularity of the war resulted in U.S. extrication becoming the primary strategic goal. Washington directed American military commanders in Vietnam to turn the war back over to their South Vietnamese allies under a new policy called "Vietnamization." And it was clear that "sooner" outranked "later."

For the Navy's part, Admiral Zumwalt responded to this new directive by creating a graduated, on-the-job training program that he dubbed ACTOV (Accelerated Turnover to the Vietnamese). ACTOV got underway in late 1968 and proceeded at a steady rate thereafter, putting the Navy out ahead of the other services for its part in Vietnamization. The whole process took less than a year.

It had been a strange cycle that had begun with U.S. Navy personnel arriving in South Vietnam to serve as advisers to the VNN, then shifting to full combat operations in the middle years, only to be later returned to the role of advisers at the end.

Preparing for war with the Soviet Union during the Cold War had required the building of a powerful blue-water navy in a classic blend of the traditional strategic concepts of deterrence, sea control, and forward presence. And when it came time for power projection in Vietnam, the blue-water giants were more than capable of launching strikes against the communist North. But the Navy was ill-prepared for the green- and brown-water operations needed in the South. Consequently, appropriate vessels had to be created by conversions, tactical doctrine had to be developed in the crucible of combat, and many of the sailors who went in-country had to learn skills well outside their ratings. The in-country Navy had been an aberration, a jury-rig of sorts, and ultimately it was for naught.

But it was also a triumph of American adaptability and of the Navy's traditional "can-do" spirit. Despite numerous handicaps, the needed forces not only coalesced in relatively short order but were effective in turning the tide of battle in several specific areas. Infiltration from the sea was significantly reduced by Operation Market Time, vital waterways were kept open by Operation Game Warden, and enemy forces were pushed back into the hinterlands of the Mekong Delta and the Rung Sat Special Zone by the Mobile Riverine Force. And Operation SEALORDS combined the Navy's in-country assets into an aggressive assault on those forces that continued to infiltrate from the Cambodian sanctuary.

Most of the 2,663 Navy and 7 Coast Guard personnel who died in Vietnam - and thousands more who were wounded - were casualties of these anomalous operations, but for most of the in-country sailors who survived, our service was (and remains) a source of pride. And, as the years have passed, the in-country experience has lingered as an assortment of surreal memories, occasionally resurrected by the sound of a passing helicopter, or the sight of a dripping palm frond, or the ominous rumble of distant thunder.

Article courtesy of USNI.org