Coast Guard Lt. Cmdr. Paul A. Yost, Jr., later a Commandant of the Coast Guard, was leading a group of 13 swift boats during the insertion of Navy Underwater Demolition Team-13 and some Vietnamese marines when his column came under attack from a Viet Cong ambush that managed to heavily damage multiple boats, kill American and Vietnamese troops, and isolate the last boat.
When Yost found out that his last boat was trapped in the kill zone and his other ships weren't in shape to recover it, he took his command boat and one other back into the kill zone to rescue the sailors who were still under attack.
The 13-boat movement was part of Operation Silver Mace II, which was put into action to break up Viet Cong operations in that section of Vietnam. The boats were to drop off the ground forces and then provide support from the river. The first five boats reached the insertion points for their marines and completed their mission without incident.
The other eight boats continued upriver. When they went to drop off their marines, a U.S. Marine major assigned as an advisor went to Yost and asked that the Vietnamese marines be dropped another mile upriver because the going was hard and no Viet Cong activity had been spotted. Yost agreed.
Just to be safe, Yost ordered the two Seawolf attack helicopters assigned to him be launched. They were based on a ship 15 minutes away, meaning they would arrive as the boats got to the more dangerous parts of the river.
But Yost's superior, Navy Capt. Roy Hoffman, ordered the helicopters to sit tight, possibly to ensure that they wouldn't run out of fuel before they were needed. Yost wasn't told of the change.
A short time later, everything went sideways. The eight boats were proceeding upriver when PCF-5, the lead boat, was suddenly hit with a claymore mine from the riverbank. More claymores, rockets, and machine gun fire rained down on the boats.
Yost was in the second boat and ordered it to push through the kill zone, and the rest of the column followed.
The rear boat, PCF-43, was the slowest and needed maintenance, according to then-Lt. j.g. Virgil A. Erwin III — a boat commander during the operations. In addition to its maintenance issues, it was weighed down with 800 pounds of explosives, 10 UDTs, and all of their gear.
That boat was unable to keep up with the rest of the column as they pushed through the kill zone, and it was left as the sole target for a few fatal seconds during the ambush. The corpsman on board was hit with a rocket and killed just before another rocket struck the cabin, killing the boat commander and severely wounding the two others in the cabin.
The boat ran out of control and beached itself, hard, on a mudbank. It hit so hard that it slid most of the way out of the water, leaving the engine's water intake above the waterline and making it impossible for the boat to propel itself back off.
As the engine overheated, the UDT members jumped from the boat and established a defensive perimeter behind it, using the wreck as cover from the Viet Cong fire coming from a mere 20 feet away.
The closest boat, PCF-38, attempted to assist PCF-43, but their steering gear was damaged and they were forced to head back upriver. Once they reached the lead perimeter, they alerted Yost to the state of PCF-43.
Yost took his craft, PCF-31, and the former lead boat, PCF-5, back downriver. Once they reached the ambush site, 5 and 31 began pouring .50-cal. rounds into the jungle and forced the Viet Cong fighters to take cover. As 5 kept the fire up, Yost and 31 pulled up to the stricken 43 and began evacuating the wounded and dead.
The two crafts escaped with 15 survivors and the bodies of the two men killed in action.
Just a few hours later, PCF-43 exploded. The most likely cause was that the engines, which typically were cooled by water flowing through the engine for propulsion, had overheated and set fire to the leaking fuel. The fuel ignited the explosives and the whole thing burned hot until the boat itself exploded.
Yost was later awarded the Silver Star for his part in the fight. In 1986, he became the 18th Commandant of the Coast Guard.