Fifty Years Ago: A Simple and Deadly Tactic almost Fells the "Wesco"

The virtually undetectable weapons that almost destroyed a Landing Ship, Tank (LST) of the Mobile Riverine Force?  

You're looking at them.

(Photograph captured from the Viet Cong in 1971 by Australian forces/ Australian War Memorial) 

Historians of the Vietnam War have recognized the nature of riverine warfare during the war in Vietnam as comparable to that experienced by the U.S. Navy during the Civil War.  The vessels of the Mobile Riverine Force (MRF) in the Mekong Delta in South Vietnam faced the same sorts of threats that Navy gunboats on the Mississippi or the James River faced more than a century earlier. Aside from larger mass-produced Soviet and Chinese mines that teams of Viet Cong (VC) sapper-swimmers deployed in larger waterways such as Soirap River–the maritime lifeline to Saigon–small man-portable improvised explosive devices, mines and satchel charges carried by enemy Viet Cong  sappers were the bane of the MRF in smaller rivers across South Vietnam, particularly in the Mekong Delta.

Former Acting Director of Naval History Edward J. Marolda wrote that this picture of River Assault Division 91 monitors taken in the Mekong Delta in 1968 was evocative of "Civil War combat on the Mississippi." (Naval History and Heritage Command image)

In 1966, intelligence estimates indicated that about half of the population of the Delta were under VC control. In the two years since then, the Viet Cong’s hold over the area, home to approximately 40 percent of South Vietnam's population, was markedly degraded by the MRF. The late summer and early fall had been very successful, with a longstanding VC stronghold in the U-Minh Forest 48 miles southwest of Can Tho falling to them in August.  Yet the enemy turned out to be far more elusive than originally expected thanks to their reliance on stealth and their light footprint compared to the Americans and their Vietnamese allies.

Not only were smaller fiberglass-hulled river patrol boats (PBRs) and armored support patrol boats (ASPBs) vulnerable to small “limpet” mines borne by the enemy sappers, American Sailors found that even the larger vessels used as bases for the MRF, also known as Task Force 117, were highly susceptible to attack, the most deadly of which occurred fifty years ago.

Similar in size, displacement and role as USS Westchester County (LST 1167) during the war, USS Vernon County (LST 1161, foreground) serves somewhere in the Mekong Delta with other large vessels of the Mobile Riverine Force (MRF), including self-propelled barracks ships (APBs) and a large barracks barge.  Vernon County was a tempting target for VC sapper-swimmers due to its role as a floating warehouse, carrying 600 tons of ammunition as well as fuel. All of the LST's gun mounts were manned during nighttime hours, and six sentries stood watch over the pontoons moored alongside. (National Archives and Records Administration)

It was 0322 on November 1, 1968, and all was quiet for the 132-man crew aboard the Landing Ship, Tank Westchester County (LST 1167), along with 175 Soldiers of the 9th Infantry Division's 3rd Battalion, 34th Artillery Brigade who were billeted aboard, off-duty Sailors of Navy River Assault Division 111, as well as Vietnamese military personnel operating with the Americans. Known as the “Wesco” to those who served aboard the LST, Westchester County had operated out of Hampton Roads for the first four years of her service career, but ten years after departing Naval Amphibious Base Little Creek for a new homeport in Yokosuka, Japan, Wesco was attached to Task Force 117, Mobile Riverine Group ALPHA (responsible for the Eastern Mekong Delta) and was on its fifth combat deployment to Vietnam, serving as a base on the My Tho River, 40 miles north of Vung Tau.

USS Westchester County (LST 1167) photographed in Naha, Okinawa, by USS Washoe County (LST 1165) crew member Rich Krebs in 1966. (NavSource Online)

The ship wasn’t just a place to tie up and sleep. Wesco was crammed with 350 tons of ordnance and fuel as part of a self-sufficient floating base that included the command ship Benewah, itself a converted LST, along with the repair ship Askari, two barracks barges, and salvage vessel. Atop the ship were five Army UH-1 Iroquois “Hueys,” fueled up and ready to dust off at a moment’s notice. Along Wesco’s entire tank deck, just above the waterline, were more than 10,000 105mm and 155mm shells, thousands of rounds of 20mm ammunition, stacked boxes of C-4 plastic explosive, Claymore antipersonnel mines, white phosphorous ammunition and a variety of flares.

Tied along Wesco’s 384-foot-long hull were three large ammunition and fuel barges called “ammis,” separated from the hull by a large teak log “camel.” Tied up to the ammis were approximately 25 armored river monitors, ASPBs, and armored transports (ATCs) of the river assault division.

The B-40 rocket (also known as the RPG-2, as popular as the RPG-7 is to the Taliban in Afghanistan today) was a weapon of choice for VC attackers while the vessels of the division were on patrol, but a countermeasure in the form of bar armor (which can be seen today on some Stryker armored vehicles) was helping defeat the shaped charges of the B-40. Far harder to detect and defeat, even at the heart of the floating base complex, was the stealthiest yet most primitive weapon used against them: VC sapper-swimmers, most wearing only briefs, breathing through small snorkels, and armed with only limpet mines, many of them improvised.

Two Viet Cong control-type mines discovered by a Mobile Riverine Force patrol.  Undated. (Commander T.L. Sinclair/ Naval History and Heritage Command image)

Picket boats wound their way around and through the group of ships, their crews randomly dropping concussion grenades into the water in an attempt to thwart the swimmers, yet at least two got through, setting off a pair of mines estimated to have contained between 150 and 500 pounds of explosive each at the ship’s weakest point, just below the waterline between Westchester County’s hull and the extremely vulnerable aluminum-hulled ammi pontoon barges.

Shards of the disintegrated teak camel, steel, and aluminum shot out in all directions, yet much of the force of the simultaneous explosions was channeled upward, sending the entire LST reeling and almost flipping one of the ammi barges completely over. The survivors in the devastated second and fourth deck berthing areas woke up to a grim reality–ammunition was scattered everywhere and the air hung heavy with vaporized diesel fuel, threatening a secondary explosion much more devastating than the first. River water poured into the ten-foot-wide holes made by the mines, threatening to capsize Westchester County.

Wesco’s commander, Lieutenant Commander John Branin, was grappling with several competing problems. Thrown onto the deck by the initial explosion, he called for general quarters to be sounded, only to find that many of the more senior petty officers; the ones whose leadership was vitally needed to run the LST’s battle stations, had been in the berthing area nearest the blasts. He quickly ascertained that the explosions were not part of some larger, coordinated attack and diverted his attention towards correcting the list. Fortunately, LSTs were designed with enhanced ballasting capabilities, capable of sinking and refloating the LST in order to take on and disgorge armored vehicles in a littoral environment. If Branin could selectively purge the right voids on the starboard side, he could stem the list and save the ship.

Just then, Petty Officer 2nd Class Rick Russell made contact with the bridge via sound-powered phone. Miraculously, the detonations had spared the forward ballast tanks and the electric pumps seemed to be operational. Wesco’s damage control officer guided Russell though the process of pumping water out of the forward tanks on the starboard side, and the ship slowly began to right itself.

In all, 18 American Sailors, five American Soldiers, one Vietnamese sailor and one Vietnamese army Tiger Scout were killed, plus a further 27 were wounded. Two of the Army choppers on its flight deck were also destroyed. While Wesco was saved from capsizing, several other existential threats remained. Cutting torches could not be used to free the Soldiers and Sailors still trapped in the berthing compartments. In fact, any spark could still destroy the rest of the vessel as well as the River Assault Division boats still afloat. Standard damage control implements had to be used to free the wounded and recover the fallen until the ship was thoroughly ventilated.

Several days after the attack, Wesco still maintained a pronounced list and the true amount of damage had yet to be ascertained, so Lt. Cmdr. Branin reluctantly beached the LST on November 4 in order to complete damage assessments and affect necessary repairs. Working around the clock, Wesco’s crew along with that of the repair ship Askari and a team set from Naval Support Activity Dong Tam built a cofferdam around Wesco’s starboard side to expose the entire damaged area for necessary repairs.

Just ten days later, Westchester County was on its way back to Yokosuka and, ultimately, back to the United States for extensive repairs.  Wesco completed more deployments to Vietnam in support of Operations Market Time and End Sweep before being decommissioned on August 30, 1973.

The ship that nearly met its end in Vietnam 50 years ago served the Turkish navy for another three decades before being decommissioned for the last time in 2004, succumbing to at least two Hellfire and one Sea Sparrow missile during a training exercise on May 30, 2014.