by PAUL HUARD

It was shortly after midnight when two Viet Cong commandos emerged from a sewer tunnel that emptied into Saigon Port, each man carrying nearly 90 pounds of high explosives and the components needed to make two time bombs.

Their target was the largest American ship in port, USNS Card. An escort carrier that saw distinguished service as a submarine-hunter in the North Atlantic during World War II, during the early morning hours of May 2, 1964, Card was part of U.S. Military Sealift Command.

The ship supported an escalating military commitment of the South Vietnamese government that occurred well before the Tonkin Gulf Incident. Since 1961, Card had transported both fixed-wing aircraft and helicopters to the beleaguered nation as well as the U.S. pilots and support crews need to operate them.

The commandos swam toward Card, where they spent about an hour in the water attaching the charges just above the waterline near the bilge and the engine compartment on the ship’s starboard side. They set the timers and quickly swam away.

The charges exploded. Five civilian crewmen on board Card died, the explosion tore a huge hole in the engine-room compartment and a proud ship that had survived German U-boat attacks was on her way to the bottom — the last aircraft carrier in U.S. military history to date sunk by enemy action.

The sinking of the Card was stunning victory for the Viet Cong, yet little remembered today. It illustrated how vulnerable naval vessels can be even when faced with a low-tech enemy … and how difficult maintaining port security can be in a war with no real front.

But it also demonstrated how resilient American naval forces are. In 17 days, salvage crews raised Card out of nearly 50 feet of water, and six months later the ship returned to service for another six years.

Not surprisingly, North Vietnam celebrated the sinking of Card, considering it a propaganda victory of the first rank. The U.S. government refused to even acknowledge the vessel’s sinking, telling the public the carrier had only been damaged.

The North Vietnamese government even commemorated the event by portraying the operation on a 1964 postage stamp.

Naval vessels often have a mystique about them — they look formidable, bristle with weapons and aircraft, and have the ability to project a nation’s power anywhere on the planet.

In particular, aircraft carriers are the symbol of a nation possessing “great power” status.

But they are vulnerable to attack. For example, there are reasons why even aircraft carriers have numerous escort vessels — destroyers, guided-missile cruisers, even submarines — to protect a carrier as well as engage the enemy.

We shouldn’t be too surprised when an enemy takes out a naval vessel in combat, even if it is a commando with a time bomb, James Holmes, a naval historian and analyst who teaches at the U.S. Naval War College, told War Is Boring.

“We shouldn’t get carried away with thinking of warships as ‘castles of steel,’ or latter-day dreadnoughts, or whatever,” Holmes said. “A castle is a fortification whose walls can take enormous punishment, whereas most modern warships have thin sides — the nuclear-powered carrier being an honorable exception. So a guy with a charge can do a lot of damage.”

Holmes said the sinking of Card “provided a preview” of the attack on the USS Cole in 2000 — a textbook case of a low-tech assault taking out a prime example of U.S. naval might.