Operation JACK STAY: US Marines in the Forest of Assassins

Today’s post is by Nathaniel S. Patch, Reference Archivist at the National Archives in College Park, MD and Subject Matter Expert for Navy Records.

Section I: Enemy at the Outskirts

On February 27, 1966, the Panamanian cargo ship, SS Lorinda, was sailing up the Long Tau River heading towards Saigon. The Long Tau is the deep channel passage to Saigon, but is one of several rivers that flow down from Saigon into the South China Sea. Before entering the main channel of the Saigon River, these rivers flow through a large mangrove swamp called the Rung Sat.

As the SS Lorinda made her way up the river, the dense jungle forest erupted in an attack. From the west bank of the river, members of the National Liberation Front (NLF), or more commonly known as the Viet Cong, began their ten minute attack with small arms fire from 7.62mm machine gun and 57mm Recoilless Rifle fire. Ten recoilless rifle rounds hit the ship, wounding three sailors including the master of the ship. The Lorinda was badly damaged and ran aground. She was later refloated and towed to Saigon. Four days later, on March 3, SS Paloma, a Vietnamese flagged oil barge was attacked about 3 km from where the Lorinda was attacked. This attack was similar with a combination of machine gun and recoilless rifle fire. Struck at the waterline, the Paloma was forced to be towed into Saigon, but the message sent a warning to those who would support the regime in South Vietnam and the Americans.[i] The attacks on the SS Lorinda and SS Paloma were the beginning of a Viet Cong campaign on shipping along the Long Tau River and the widening of the Viet Cong’s insurgency war against South Vietnam and their American supporters.

The US Military response to these attacks along the shipping lanes to Saigon was to plan and conduct an amphibious landing to sweep the Rung Sat area where they thought the Viet Cong were operating from. This first operation into the Rung Sat Special Zone in March and April 1966 was known as Operation JACK STAY. The records that describe the planning and execution of these landings can be found in Record Group 127: Records of the US Marine Corps and Record Group 472: Records of US Forces in Southeast Asia. Some of these records are available online on the National Archives Catalog in the digital collections of the US Marine Corps Command Chronologies (Entry UD-07D 1) in RG 127 and in the Deck Logs (National Archives Identifier 594258) of the supporting vessels during the landings in Record Group 24: Records of the Bureau of Naval Personnel in Entry P 118-E. There are more online US Navy and Marine Corps resources that are available on the Records of War website.

Command Chronology Report of 1st Battalion, 5th Marine Regiment, February-May 1966 (National Archives ID 2435599). Page 109.  

Section II: Rung Sat Special Zone – Environment and Terrain 

Of the regions of South Vietnam, the Rung Sat area posed one of the greatest challenges to the Military Assistance Command, Vietnam (MACV) and Government of South Vietnam (RVN). The Rung Sat is a 400 square-mile densely forested mangrove swamp southeast of Saigon. The area in the tidewater area of the South China Sea creates numerous small streams and mud flats, and is overgrown with mangrove trees and nipa palms with a thick brushwood jungle. There are also paddy fields where rice can be grown.[ii]

There are two primary seasons in the Rung Sat area; a wet season and a dry season. The wet season is May through October, while the dry season is December to March. April and November are when the seasons transition.[iii]

The weather in the Rung Sat is fairly consistent with temperatures in the 90’s and above during the day and 70’s during the night. The wet season has approximately 80% or more humidity, and during the dry season it can be as low as 20% humidity.

In terms of the resident population, the Rung Sat had a population of about 16,000 people in villages and New Life settlements, a modification of the protected hamlets from the Diem regime. The people of the Rung Sat were fishermen, farmers, and woodcutters.[iv]

Command Chronology Report of 1st Battalion, 5th Marine Regiment, February-May 1966 (National Archives ID 2435599). Page 187.

The mangrove swamp near Saigon of Rung Sat, meaning “Forest of Assassins”[v], was given its moniker because it’s long history of being a haven to thieves, bandits and anti-government elements long before the French-colonization of Indo-China. The dense forest provided a haven to a variety of people prior to the Viet Cong, including Japanese soldiers who refused to surrender after World War II. During the 1950’s, the Vietminh attacked the French, and during the brief peace between 1954 and 1965, members of the opposition party, the Binh-Xuyeu, built a fortified camp and fought battles against the Diem regime.[vi]  

Besides the dense forest, the Rung Sat has one other strategic value; four river ways that connect Saigon to the South China Sea: the Long Tau, Soi Rap, Vam Sat, and Cat Lai Rach La Rivers. Control of the Rung Sat area means control of the water traffic going in and out of Saigon. The Vietminh exploited this weakness during the First Indo-Chinese War, and the French had to constantly patrol and sweep the shipping lanes for mines.[vii]

The US military associated the new Viet Cong activity in the Rung Sat as a continuation of the Vietminh operations. However, between the end of the First Indo-Chinese War in 1954 and the beginning of the Second Indo-Chinese War in 1964, military activity in the Rung Sat area was reduced to harassment of the New Life villages and basic banditry of the local population. The Viet Cong and North Vietnamese forces did not resume real interest in the Rung Sat area until 1965, when a North Vietnamese engineer battalion was sent down to begin construction of fortifications and other developments, including schools, hospitals, and weapons factories. The region was official designated Doan-10 (Group 10 or T-10) and declared the Rung Sat Special Zone (RSSZ).[viii]

Between the central core of North Vietnamese troops who comprised the leadership, and the local Viet Cong forces recruited from near-by villages and hamlets, the force within the Rung Sat swelled to over a thousand personnel. The two primary missions of these units were to interdict shipping going to Saigon, and to create a haven for the Viet Cong forces. By February 1966, the Viet Cong forces were prepared and capable of conducting their anti-shipping missions. It would not be until the Marines foray into the Rung Sat that the US military would come to realize how entrenched the Viet Cong were.

Section III: Expansion of the War and the Protection of Saigon

In July 1965 when the US government escalated the war in Vietnam, US Marine forces were sent in. The two major commands with the Marine Corps in Vietnam were the III Marine Amphibious Force (III MAF) and the 9th Marine Amphibious Brigade (9th MAB). At the time, the III MAF had the operational control of the I Combat Tactical Zone (CTZ) or I Corps area. The 9th Marine Amphibious Brigade was responsible for the mobile forces of the Marine Corps based out of Okinawa and units afloat as the Special Landing Force (SLF). The SLF initially planned to be the ready reserve to assist ground forces that were in Vietnam.

The SLF was a Marine battalion that embarked aboard three amphibious ships, re-enforced by a Marine helicopter squadron, detachments of artillery, amphibious tractor, and tank units.[ix] During the period of March and April 1966, a re-enforced 1st Battalion of the 5th Marines[x] and Medium Helicopter Squadron 362 (HMM 362) were afloat aboard the USS Princeton (LPH 5), USS Alamo (LSD 33), and USS Pickaway (APA 222).[xi]

After the attacks in February, it was determined that the Viet Cong seized control of the Rung Sat area and could freely attack shipping along the Long Tau River, the main shipping channel. The US Navy and Marine Corps Pacific Fleet commands met in Okinawa to develop amphibious doctrine for in-country operations. This conference analyzed the lessons from the earlier DAGGER THRUST operations during 1965 where SLF landed forces for 1 to 2 day operations against the VC and also settled on a chain of command between the SLF and units of the III MAF.[xii]

The planning for Operation JACK STAY began in the second week of March 1966, a conference of MACV, the Naval Advisory Group, 7th Amphibious Force, and Special Landing Force was held in Okinawa. The conference developed a strategy to address the Viet Cong in the Rung Sat area and rout them out. The interdiction plan included amphibious operations by the SLF, and support from Marine Reconnaissance units, US Navy SEALs, Underwater Demolition Teams (UDT), riverine vessels from Task Force 115 Operation Market Time, two South Vietnamese Marine battalions, and US Army and Marine helicopter squadrons. Ships of the 7th Fleet provided air and gunfire support during the raid. [xiii] The strategy was to envelop Viet Cong in the Rung Sat, closing them off from the rest of the country and launching a series of search and destroy raids into the interior of the forest to force them out.[xiv] This concept of attacking Viet Cong strongholds using the SLF had been met with limited success during 1965 with Dagger Thrust style amphibious landings in a surgical and narrowly defined area opposed to the broader beachheads of World War II. Like the earlier Dagger Thrust operations, Operation JACK STAY was planned with a window of a few days to complete the objectives and withdraw. JACK STAY was planned to open with a simultaneous amphibious landing on the shores of Long Thanh peninsula and Marines heliolifted to different landing zones to the north and west to surround the area. [xv]

Section IV: D-Day and the Sweeping of Rung Sat

JACK STAY was planned for March 26, 1966 and consisted of two phases. Phase I was to establish a base camp in the Rung Sat area to conduct search and destroy missions using amphibious and helioborne landings. Phase II was to conduct in-depth searches for VC forces and infrastructure within the Rung Sat and incapacitate the VC’s presence and logistics. In preparation of the landings, naval surface ship bombardment and air strikes softened the landing area referred to as Red Beach on the peninsula.[xvi]

Prior to the beginning of Phase I, the area of Rung Sat was pounded by air strikes from the USS Hancock (CVA 19) and USS Kitty Hawk (CVA 63) an hour before the landings were to begin. UDTs from the USS Weiss (APD 135) performed beach reconnaissance to make sure that Red Beach was prepared prior to the Marines arrival.[xvii] Just like in World War II and Korea, UDTs were used to prepare areas prior to an amphibious landing to ensure there were no natural or man-made obstacles that would hinder the landings. Small patrol craft of Market Time forces (Task Force 115) coastal surveillance patrolled and surrounded the Rung Sat area to prevent the Viet Cong from withdrawing from the area through use of the river system.[xviii]

Command Chronology Report of 1st Battalion, 5th Marine Regiment, February-May 1966 (National Archives ID 2435599). Page 117.

Phase I began on the morning of March 26, with landings at Long Thanh Peninsula and Marines being heliolifted to zones east of the amphibious landings. Due to mechanical problems with some of the LCMs aboard the the USS Alamo, the landings were delayed. The landing craft were planned to depart at 0630 and sail to Red Beach on the western tip of the Long Thanh Peninsula. With an eight-mile voyage from ship to shore, the Provisional Company did not arrive until 0715, with the first wave being completed until 0835. This delay prevented the second wave with Battery D of the 2nd Battalion, 11th Marines from landing, and they had to wait until the next high tide at around 1700 that evening.[xix] 

The Provisional Company landed 600 meters east from the designated area of Red Beach. The landing was unopposed with the only sign of enemy activity being the discovery of the body of a fisherman that had been identified as kidnapped by the VC.

With the amphibious landings delayed, the helicopters of HMM 362 departed the USS Princeton at 0720 and heliolifted Company A to Landing Zone (LZ) Robin and Company C to Landing Zone (LZ) Sparrow. When Company A arrived at LZ Robin, a central position about midway along the peninsula, they established a defensive perimeter and prepared for Company B and D’s arrival in the second wave. Company C at LZ Sparrow, the eastern most position on the peninsula and just west of the town of Can Gio, set up blocking positions in the event the Viet Cong should retreat from the sweeping operations of Red Beach and LZ Robin.[xx]

Companies B and D were taken to LZ Robin during the second wave of heliolifts from the Princeton. Company B swept the area from LZ Robin east towards Company C, and Company D swept west towards the Provisional Company at Red Beach. Additionally, an 81mm mortar platoon and 107mm howtar[xxi] company was lifted to LZ Robin to provide artillery cover. At Red Beach Battery D of 2nd Battalion, 11th Marines landed to provide artillery cover from the west.[xxii] To augment the artillery units ashore, aboard the Henry County (LST 824) was armed with three ONTOS, a Marine tracked vehicle armed with four 106mm recoilless rifles as makeshift batteries.[xxiii]

It was said that the Viet Cong owned the jungle at night. This was a very real threat. To help assist the beachhead, 21 teams made up of Navy UDT and SEALs, and Marine Reconnaissance teams were landed by the Weiss in the late evening and moved north of Red Beach for the purposes of scouting ahead and preventing Viet Cong movement, either towards the landing area or out of the Rung Sat. They were picked up the following morning.[xxiv]  

The second day of the operation continued to set up Phase I. Company B swept and connected with Company C at LZ Sparrow, and Company D swept and connected with the Provisional Company at Red Beach. Throughout Day One and Two, the Marines encountered limited VC activity, but took some casualties. One Marine was killed by a sniper, while another died from his wounds from a skirmish on the evening of the first day. On the morning of the second day, the Marine casualties were one Marine killed and another wounded. The number of VC encounters were sporadic, from individuals to groups as big as 40 men. The Viet Cong was also taking casualties from their encounters with the sweeping Marines and their probing into the landing zone areas.[xxv]  

On the afternoon of March 27, the companies of the SLF moved around like knights on a chess board in preparation for the beginning of Phase II. Companies A and C were moved by helicopter to Red Beach where they boarded Washoe County (LST 1165). Company B took over for Company A at LZ Robin and Company D took over for the Provisional Company at Red Beach. The Provisional Company and Battery D (11th Marines) were heliolifted from Red Beach to LZ Robin.[xxvi]

On March 28, at 0900, Phase II opened up with the roar of an Arclight Strike of USAF B-52s at Blue Beach, an area along the Soi Rap River on the northern part of the Ly Nhon Peninsula. From the Washoe County, Companies A and C landed on Blue Beach at 0955, and found a number of mines and booby traps destroyed by the air strike. South of Blue Beach, the Provisional Company (minus two platoons) and 107mm Howtar Battery heliolifted to LZ Bluejay. Far to the east, Company D heliolifted to LZ Blackbird, which was about five miles north of LZ Robin on the Long Thanh Peninsula. There, Company D established a defensive position because the area was too marshy with waist-deep water to conduct productive sweeping positions. From LZ Robin, Battery D with two platoons from the Provisional Company provided artillery cover for LZ Blackbird.[xxvii]

On March 29, the Special Landing Force was enveloping the Viet Cong from the south and west with established fire bases at Red Beach, LZ Robin, and LZ Bluejay. As they crept up the Ly Nhon Peninsula, the command post at LZ Robin was heliolift to a bend in the Soi Rap River north of Blue Beach to establish LZ Crow. Companies B and D, and part of the Provisional Company with Battery D were relocated to LZ Crow to prepare for next part of the operation. Company D was moved from LZ Blackbird. Two platoons of the Provisional Company, Company B and Battery D were heliolifted from LZ Robin to LZ Crow.[xxviii]

On March 30 Companies A and C swept east from Blue Beach towards the Vam Sat River, a small river that cuts through Ly Nhon Peninsula, and whose mouth is just north of Blue Beach.[xxix]

On the morning of March 31, the second large landing craft convoy assembled near the Henry County, including seven LCMs, two LCVPs, two French-built river landing craft France d’Outre Mer (FOM) and Vietnamese river monitors.[xxx] To address any possible mines in the river, two specially outfitted LCVPs were jerry-rigged into minesweepers. And in the event of any material losses, an American landing craft was rigged as salvage vessels. The convoy was escorted by armed Army and Marine helicopters.[xxxi] 

Companies B and D were transported down the Vam Sat River to the mouth of one of the smaller rivers within the Rung Sat called Lo Ren River. As the convoy progressed into the Vam Sat, the tension of the voyage was broken by the remote detonation of a mine. It did not damage any of the landing craft or monitors, but it announced the opening of the VC ambush. The Marines aboard the landing craft and the 40mm guns of the monitors responded, firing into the forested banks of the river. The reciprocal fire quieted the VC attack, causing them to withdraw. Fortunately, no one on the convoy was injured.[xxxii] 

During this convoy and other transits down the rivers, the US Army and Marine helicopters proved to be invaluable at protecting the landing craft on their voyages. They conducted “reconnaissance by fire” by flushing out VC units when they began to shoot at the helicopter hovering overhead. When a helicopter was attacked, other helicopters would arrive to drive off the VC with suppressive fire.[xxxiii]  

At the end of the eight-mile voyage, the LCMs deposited Companies B and D at the point where the two rivers meet at Rach Bagiong. The empty convoy then returned to the Vam Sat River and briefly headed south to pick up Companies A and C, who had finished clearing the area on the western bank of the river. The convoy returning to Washoe County and LZ Crow were harassed by Viet Cong with small arms fire. The convoy and Marines responded in kind by shooting their rifles from the gunnels of the landing craft. Again, the VC withdrew without injuring anyone on the convoy.[xxxiv]

The Henry County shifted her position in the evening in order to better support the Companies B and D with harassment and interdiction fire against the Viet Cong.

After making their landing, Companies B and D made inroads into the Rung Sat and VC’s area of operation. The Marines found and destroyed 18 carbines and 1,000 grenades. They located arms manufacturing centers complete with heavy bunkers, numerous tunnels and equipment so large that it defied reason on how small sampans brought all this equipment and material into the middle of a swamp. Demolition experts were busy destroying anything of value. The following day, the two companies discovered more camps finding caches of arms, supplies, casings for mines and 105mm shells, and another arms manufacturing factory. They were so busy that the demolition experts had to have more explosives flown in on the following day, April 1, to complete the job.[xxxv]

April 1 proved to be another busy day for everyone. As demolition teams continued to destroy VC facilities, Company B with assistance from engineers, destroyed 300 pounds of cast iron, 13 acetylene tanks, 400 mine casings, and numerous amounts of grenades and mortar rounds. Company D discovered the headquarters of the VC chief, which contained large caches of gunpowder, primers, solder wire, and 150 sheets of brass. There were jugs of oil and 100 steel rods along with other equipment.[xxxvi] During the same period, Companies A and C swept south from LZ Crow.[xxxvii] 

For the Navy, the USS Robison (DDG 12), Market Time swift boats, and LCPLs were kept busy exchanging fire with VC units on shore. Most of the contacts were made in the southern part of the Rung Sat area at the confluence of the Soi Rap and Long Tau rivers near Nha Be. The 5-inch guns of the Robison shattered the VC attacks.[xxxviii] Near midnight, the Market Time forces who had been guarding the river approaches and exits to the Rung Sat got a terrible fright when they spotted 55 junks moving down river towards the Washoe County. They feared an attack was eminent because the commanders of the Special Landing Force and river units knew there were operations scheduled for that night. After some tense moments, it was discovered that the large group of vessels was merely an un-announced convoy being escorted by the Vietnamese Navy.[xxxix]

On the nights of April 1 and 2, battalions of the South Vietnamese Marine Corps were introduced into the operation. On the evening of March 31, 5th Vietnamese Marine Battalion embarked in LCMs at Cuu Long, and made an amphibious landing at Tam Hiep Thon, northeastern area of Rung Sat early the next morning. They swept the area, but had no contact with the enemy. In subsequent days, they attempted to make contact with the enemy making additional landings in the area.[xl]

On April 2, US Marine Companies A and C continued to move southwest towards their objective. They destroyed VC huts, water containers, and booby traps as they went. However, they did not make contact with the enemy as they swept through the area.[xli]

At LZ Bluejay, the Provisional Company discovered and destroyed 84 4-foot by 4-foot mud bunkers that were five meters within the tree line of the landing zone. Despite being made from mud, these bunkers withstood a direct hit from 3.5-inch HEAT[xlii] rocket from 100 yards away.[xliii]

April 3 was a day marked by astonishing discoveries, most notably the impressive capacity of the Viet Cong to establish themselves within the density of the jungle. The day began with the companies continuing their sweeping out from LZ Crow on search and destroy missions. Company A, combined with demolition engineers, returned to the camps and bunkers they had found the day before and set about destroying them. In their sweep, Company C discovered a VC training area, including classrooms and bunkers. If that was not enough, they later found a hospital complex large enough for 200 people with numerous huts and electric lights powered by a gasoline generator, and a complex of bunkers connected through tunnels.[xliv]

Company B discovered and destroyed 60,000 rounds of 7.92mm rounds, grenades, mine castings, boats, huts, and food and supply stores. Later they discover a small boat repair center.[xlv]

Company D discovered a training area with several jugs of oil. Later, they found a base camp that had been recently vacated. The discovered base complex had a factory for making mines, as well as work sheds, sleeping areas, classrooms, a dispensary, and series of outlying bunkers. Among the buildings, they found a wide variety of tools, about 300 mines, and large amounts of food and supplies. The company set about destroying this complex.[xlvi]

Command Chronology Report of 1st Battalion, 5th Marine Regiment, February-May 1966 (National Archives ID 2435599). Page 119.

After another night of no VC contact, the morning of April 4 saw the continuation of Companies A, B, and D sweeping towards the Vam Sat River and then returning back LZ Crow. Company C spent the day destroying the VC hospital complex they discovered the day before. Navy UDT personnel assisted in the demolition of the hospital. As they set about dismantling the facility, they discovered papers, medical journals, propaganda, medicine, and other food and supply stores. By the end of the day, Company C returned to LZ Crow.[xlvii] On the same day, the 4th Vietnamese Marine Corps Battalion landed to establish defensive positions along the Long Thanh Peninsula and 5th Vietnamese Marine Corps Battalion returned to their command post at Tam Hiep Thon.[xlviii]

Section V: Wrapping Up and Withdraw

In the following days, April 5 and April 6, Operation JACK STAY was wrapping up. On the morning of April 5, the Washoe County and Henry County bombarded the Rach La River area in preparation for the last of the large river convoys. Companies A, B, and D sailed from LZ Crow down to the Rach La River in a convoy of two LCVPs and seven LCMs with two salvage boats. After landing, the companies moved toward the Long Tau River. They had very few contacts with the Viet Cong. The following day, the three companies were picked up along the Long Tau River by LCM and taken back the LSTs. The LSTs sailed to Vung Tau where the Marines were offloaded. Company A was lifted to the Princeton, and Companies B and D embarked on the Pickaway.[xlix]

During the same period, Company C finished dismantling the VC hospital and then were lifted back to LZ Crow. The following day, Company C was lifted from LZ Crow to the USS Princeton.[l]

The remaining units of the Special Landing Force at LZ Bluejay, LZ Crow, and Red Beach, consisting mainly of the artillery units from Battery D, 11th Marines and the 105mm Howitzer Battery, embarked on the LSTs and sailed to Vung Tau. At Vung Tau, the Marine units disembarked and awaited to be transferred back to the ships of the Amphibious Ready Group.[li]

April 7 was the last day of Operation JACK STAY. Market Time forces returned to Vung Tau to assume their regular duties. The Special Landing Force and the Amphibious Ready Group returned to sea to be the ready reserve. The operation resulted in the killing of 63 Viet Cong with a possible 84 additional deaths (unconfirmed), the wounding of 5 with an additional 6 (unconfirmed), and no prisoners. In comparison, the Marine casualties were 5 killed in action, 24 wounded and 2 missing in action (presumed to have drowned). There is no question the Marines were able to disrupt Viet Cong and North Vietnamese operations in the Rung Sat area by destroying several campsites, training facilities, weapons and mine factories, an impressive medical facility, as well as bounty of weapons, supplies, ammunition, and food.[lii] But was the operation a success?     

Section VI: Mission in Review and Lessons Learned

Operation JACK STAY was a success, in a manner of speaking, because the raid achieved two important goals. First and foremost, it temporarily ended the Viet Cong attacks along the Long Tau River and opened the shipping lanes to Saigon. Second, it demonstrated to the Viet Cong the lengths the US forces would go to pursue them. 

The success of Operation JACK STAY, though, can be argued on the basis of its long-term effect in the Rung Sat area and the overall security of Saigon. However, victory was temporary. The Americans and the armed forces of South Vietnam fought the Viet Cong to win a skirmish or a battle. After the fight, those forces returned to their bases or ships abandoning the area. Left unattended the Viet Cong would simply move back in. This matter of warfare was not like how it was during World War II when Marines would take an island in the Pacific. After US Forces secured an island, they left a garrison on the island to secure it and use it for their own purposes. In Vietnam, once the VC was routed from an area, the American forces were limited in how they managed that area afterwards to prevent the VC from coming back. The Marines had a counterinsurgency program called Combined Action Groups (CAGs), which left platoon-sized units in villages to work with local South Vietnam forces to protect the area, but CAGs were not used in Vietnam like an island garrison in World War II. To occupy every area including the Rung Sat would over stretch American forces and require many more Marines and soldiers, as well as have logistical systems to support them. Although not ideal, the solution was policing the area and making similar raids more frequently.

The Rung Sat Special Zone became the crossroads of several Navy operations, which were set up in the southern region of Vietnam in the Mekong Delta area referred to as either the IV Corps Area, or the IV Combat Tactical Zone (CTZ). At the beginning of the war, the constant policing of coastal waterways and inlets of South Vietnam started with Task Force 115, Operation Market Time to prevent North Vietnam and China from moving weapons, supplies, and personnel into South Vietnam from the sea. The Market Time forces participated in Operation JACK STAY by guarding the various mouths of waterways in and out of the Rung Sat with their patrol craft or Swift Boats (PCFs). With the coastal areas being policed, the next areas to police were the river systems. Although they had been officially established by Operation JACK STAY in December 1965, Operation Game Warden (Task Force 116), river patrol and interdiction along the river systems in the IV Corps area and Rung Sat Special Zone, had not received enough materials to participate. Some of the lessons learned in Operation JACK STAY would have a profound effect on Operation Game Warden’s development such as the use of LSTs as mother ships for some of the Patrol Boat (River) (PBR) detachments. According to the action report of the Amphibious Ready Group, LSTs, although large ships, had shallow drafts, which made them ideal for navigating in the muddy rivers of the Rung Sat and the Mekong. They were also good platforms from which helicopters could operate. This was one of the other recommendations from the same report, which commented positively on the use of armed helicopters to lend close-in air support. During Operation JACK STAY, armed light helicopters (UH-1s Huey) were provided by the US Army and a Marine Observation Squadron 2 (VMO 2).[liii] This recommendation may have given rise to the formation of the Seawolves, Attack Helicopter Squadron 3 (Light), or HAL 3. HAL 3 was formed out of Combat Helicopter Squadron One (HC 1) in late 1966 and became an integral part of Operation Game Warden and operations in the Rung Sat Special Zone. Two helicopter detachments were stationed on the LST mother ships and at bases up river. Their distribution across the IV Corps area made it so that air support was never too far away and could quickly respond to calls.

Section VII: Final Thoughts – Future Operations in the Rung Sat and Mekong Delta

Operation JACK STAY also established proof of the concept for the final form of policing the Rung Sat with regular infantry troops. Military Assistance Command, Vietnam (MACV) had been considering a ready landing force to address large formations of Viet Cong on land since February 1966.[liv] It was clear that the US Navy would provide the landing craft, barrack ships, and other support vessels. The question remained, however, who was going to do landings and engage the enemy? MACV wanted to chase the enemy up on shore and attack base camps built on islands in the middle of the rivers and swamps. To accomplish this, they needed troops. The Swift boats, the PBRs, and Seawolves were good at controlling the waterways. MACV encouraged Navy SEAL teams be attached to Game Warden and Market Time forces to conduct such operations.[lv] SEAL Teams were good for infiltration, counterinsurgency, reconnaissance, and maritime special warfare, but a squad of SEALs would be too small to effectively engage a large VC unit. Operation JACK STAY demonstrated that a re-enforce battalion sized unit like the Special Landing Force and the Amphibious Ready Group, could be effective either against a large force or a smaller unit forces spread out over a wide area. At the end of April 1966, MACV held a conference to determine the structure of a force that would go into the Mekong Delta and Rung Sat areas using landing craft. At first, the Mekong Delta Mobile Afloat Force, or MDMAF, was considering the newly established 26th Marines. However, the Marine Corps turned it down because the 26th Marines were still in the process of training, and would have to significantly alter the 9th Marine Amphibious Brigade to support a regimental-size landing force. They opted to continue developing the Special Landing Force, a battalion-size landing force with a complimentary helicopter squadron for quick re-enforcement when needed.[lvi]

In September 1966, Mobile Riverine Force (MRF), Task Force 117, was established. The 9th Infantry Division from Fort Riley, Kansas was preparing and training for deployment to Vietnam, and the Army selected the 2nd Brigade of the 9th Infantry Division as the landing force. The brigade went to Amphibious Training Center at Coronado, CA to train with US Navy units of the River Assault Flotilla One to form a joint Army-Navy command.[lvii] The 2nd Brigade and River Assault Flotilla One began arriving in Vietnam as early as January 1967, and was pressed into service in February.

For over two years, the Viet Cong and North Vietnam were prevented from conducting long-term operations from the Rung Sat Special Zone, in part, because of the Mobile Riverine Force. It was clear, in February 1966, that the VC had big plans in Rung Sat to choke Saigon’s shipping and harass neighboring river areas and hamlets in their insurgent war. In the dense jungle, they had built bunkers, factories, training compounds, and a hospital. The VC was able to bring in a generator and provide some electricity to these facilities. The factories built mines to interrupt shipping and light armaments for other operations. The Viet Cong counted on the Rung Sat, the Forest of Assassins, to provide them cover. The Mobile River Force policed Rung Sat Special Zone until August 25, 1969 when they stood down, but the first real challenge to the Viet Cong who burrowed deep into the mangrove swamp of the Rung Sat was the US Marine Special Landing Force in Operation JACK STAY.  

[i] MACV 1966 Command History; Entry A1 32: MACV Annual Command Histories; Record Group 472: Records of United States Forces in Southeast Asia; NACP 

[ii] Rung Sat Special Zone Intelligence Study (circa 1968); 4000105007, Carl A. Nelson Collection, The Vietnam Center and Sam Johnson Vietnam Archive, Texas Tech University retrieved April 10, 2020.

[iii] Ibid.

[iv] Ibid.

[v] Frank Uhlig, Vietnam: The Naval History (Annapolis: Naval Institute Press, 1986) p. 270.

[vi] Rung Sat Special Zone Intelligence Study.

[vii] Ibid.

[viii] Ibid.

[ix] Jack Shulimson, U. S. Marines in Vietnam: An Expanding War, 1966 (Washington, DC: History and Museums Division USMC, 1982) p. 297.

[x] Re-enforced meaning that the battalion had an additional infantry company to its regular four companies.

[xi] Shulimson, p. 300.

[xii] Shulimson, p. 299.

[xiii] Report of Operation JACK STAY dated 16 April 1966; Task Group 76.5; Task Group Reports http://www.recordsofwar.com/vietnam/usmc/USMC_Rvn.htm reviewed April 15, 2020.

[xiv] Combat After Action Report Operation JACK STAY dated 7 April 1966 from Command Chronology Special Landing Force (TG 79.5) 1 January – 31 May 1966; Task Forces http://www.recordsofwar.com/vietnam/usmc/USMC_Rvn.htm reviewed on April 15, 2020 and Uhlig, p. 348-350.

[xv] Report of Operation JACK STAY dated 16 April 1966; Task Group 76.5; Task Group Reports http://www.recordsofwar.com/vietnam/usmc/USMC_Rvn.htm reviewed April 15, 2020.

[xvi] After Action Report Operation JACK STAY dated 12 April 1966, 1st Battalion, 5th Marines Command Chronology 28 February-7 May 1966; United States Marine Corps Command Chronologies (UD-07D 1); Record Group 127: Records of the United States Marine Corps; NACP.

[xvii] Report on Operation JACK STAY; Task Group 76.5

[xviii] Report on Operation JACK STAY, Task Group 76.5

[xix] Report on Operation JACK STAY, Task Group 76.5

[xx] After Action Report Operation JACK STAY, 1st Battalion, 5th Marines

[xxi] A common name for a M98 4.2 Inch or 107mm mortar on wheels, which resembles a howitzer

[xxii] After Action Report Operation JACK STAY, 1st Battalion, 5th Marines

[xxiii] Report of Operation JACK STAY, TG 76.5.

[xxiv] Uhlig, p. 352.

[xxv] After Action Report Operation JACK STAY, 1st Battalion, 5th Marines

[xxvi] Combat After Action Report Operation JACK STAY Special Landing Force (TG 79.5)

[xxvii] Report of Operation JACK STAY, TG 76.5

[xxviii] After Action Report Operation JACK STAY, 1st Battalion, 5th Marines

[xxix] After Action Report Operation JACK STAY, 1st Battalion, 5th Marines

[xxx] LCVP sized craft with a “V”-shaped bottom.

[xxxi] Uhlig, p. 254.

[xxxii] Report on Operation JACK STAY, TG 76.5

[xxxiii] Report on Operation JACK STAY, TG 76.5

[xxxiv] Uhlig, p. 355.

[xxxv] Combat After Action Report, SLF Command Chronology and Uhlig, p. 355.

[xxxvi] After Action Report Operation JACK STAY, 1st Battalion, 5th Marines.

[xxxvii] After Action Report Operation JACK STAY, 1st Battalion, 5th Marines.

[xxxviii] Uhlig, p. 355.

[xxxix] Report of Operation JACK STAY, TG 76.5

[xl] Combat Operations After Action Report dated 22 April 1966 by Chief U. S. Naval Advisory Group, MACV/Senior Marine Advisor (liaison to VNMC units), Senior Marine Advisor MACV; Records Primarily Relating to the Vietnam War and Cold War Operations and Training, Entry A1 1009; Record Group 127: Records of the US Marine Corps; NACP.

[xli] After Action Report Operation JACK STAY, 1st Battalion, 5th Marines.

[xlii] HEAT – High Explosive Anti-Tank

[xliii] After Action Report Operation JACK STAY, 1st Battalion, 5th Marines.

[xliv] After Action Report Operation JACK STAY, 1st Battalion, 5th Marines.

[xlv] After Action Report Operation JACK STAY, 1st Battalion, 5th Marines.

[xlvi] After Action Report Operation JACK STAY, 1st Battalion, 5th Marines.

[xlvii] After Action Report Operation JACK STAY, 1st Battalion, 5th Marines.

[xlviii] Combat After Action Report Operation JACK STAY, SLF Command Chronology.

[xlix] Combat After Action Report Operation JACK STAY, SLF Command Chronology.

[l] Combat After Action Report Operation JACK STAY, SLF Command Chronology.

[li] Combat After Action Report Operation JACK STAY, SLF Command Chronology.

[lii] Combat After Action Report Operation JACK STAY, SLF Command Chronology.

[liii] Combat After Action Report Operation JACK STAY, SLF Command Chronology and Report of Operation JACK STAY, TG 76.5

[liv] Mekong Delta Mobile Afloat Force (MDMAF) dated 2 February 1966; MDMAF; Tactics and Doctrine 1966; Historian’s Background Files; Record Group 472: Records of United States Forces in Southeast Asia; NACP.

[lv] SEAL Team Employment dated January 1966; MDMAF 1966; MACV Historians Background Files; Record Group 472: Records of United States Forces in Southeast Asia; NACP.

[lvi] Mekong Delta Mobile Afloat Force dated April 22, 1966; Fleet Marine Force, Pacific Letters; Records Primarily Relating to the Vietnam War and Cold War Operations and Training, Entry A1 1009; Record Group 127: Records of the US Marine Corps; NACP.

[lvii] Naval History Division, United States Navy, Riverine Warfare: The U. S. Navy’s Operations on Inland Waters (Washington, DC: US Government Printing Office, 1969) p. 74-75.

Related digital materials in the National Archives Catalog:

March-April 1966 Deck Logs:

Hancock – http://catalog.archives.gov/id/26120577 and http://catalog.archives.gov/id/26120644

Kitty Hawk – http://catalog.archives.gov/id/70166658 and http://catalog.archives.gov/id/40450548

Weiss – https://catalog.archives.gov/id/174324406 and https://catalog.archives.gov/id/174324472

Princeton – https://catalog.archives.gov/id/174580252 and


Alamo – http://research.archives.gov/description/6705964 and


Pickaway – https://catalog.archives.gov/id/174320033 and


Robison – https://catalog.archives.gov/id/174487962 and


Washoe County – https://catalog.archives.gov/id/173581085 and


Marine Corps Command Chronologies

1/5 – https://catalog.archives.gov/id/2435599


ONTOS – https://catalog.archives.gov/id/26403128

Marines landing – https://catalog.archives.gov/id/558508