Lam Son Nao knew the sewers beneath Saigon Port the way most people know their own hallways. His father had worked at the port facility for years and had memorized every tunnel, every drain, every passage running beneath the docks where American warships tied up to unload their cargo. When the 65th Special Operations Group of the Viet Cong needed someone to sink a ship in the most heavily guarded harbor in South Vietnam, Nao was the obvious choice. Shortly after midnight on May 2, 1964, he and a fellow commando emerged from a sewer outlet, swam to the hull of the USNS Card, attached two explosive charges, and vanished back underground. The resulting blasts sank the ship in 48 feet of water and killed five crew members.
The Card had already lived one full career before arriving in Vietnamese waters. Commissioned during World War II as an escort carrier, she had hunted German U-boats in the Atlantic before being decommissioned in 1946 and mothballed with the Atlantic Reserve Fleet. In 1958 the Navy reactivated her under a new designation: USNS Card, a naval ship crewed by civilians rather than enlisted sailors. Her mission had changed from combat to logistics. Beginning in December 1961, when she left Quonset Point, Rhode Island, loaded with H-21 Shawnee helicopters and troops from Fort Devens, Massachusetts, the Card became a regular shuttle between American ports and Saigon. She and her sister ship USNS Core hauled the hardware of escalation: heavy artillery, M113 armored personnel carriers, aircraft, helicopters, and ammunition. Each arrival at Saigon Port was a visible reminder of the deepening American commitment to South Vietnam's war.
Nao held a dual identity. By day he worked as an electrician at the port facility, a job that gave him unrestricted access to the docks and a close view of every American ship that pulled in. By night he belonged to the 65th Special Operations Group, an elite Viet Cong sabotage unit. His position let him study the Card's layout, observe security patterns, and design an attack plan. His father's knowledge of the port's underground infrastructure proved decisive. The old man advised his son that the best approach to the American anchorage was through the sewer tunnel opposite Thu Thiem, across the river. Despite South Vietnamese military patrols and an elite ARVN Airborne battalion guarding the shoreline, the Viet Cong operatives in the Thu Thiem district moved with impunity. The security forces could not seal what they could not see.
The operation had been attempted before. An earlier mission against the USNS Core had failed, forcing the group to redesign their explosives and wait for another target. When Nao learned the Card had returned to Saigon, he inspected the new equipment: a fresh battery and a redesigned bomb. He chose the early morning hours of May 2 for the attack, calculating that the timing would let his team escape and avoid civilian casualties in the surrounding neighborhood. One of his planned partners fell ill, so a replacement named Hung stepped in. Each man carried 40 kilograms of explosives through the sewer tunnel. Along the way, they encountered a South Vietnamese patrol boat. Nao bribed the commander, who let them pass but demanded a second payment on their return. At the tunnel's exit, the two men assembled the explosive device, swam to the Card's hull, and attached the charges to the starboard side.
The explosion tore a hole 12 feet long and 3 feet high in the ship's starboard hull. Five civilian crew members died. The Card settled to the bottom in 48 feet of water, her superstructure still visible above the surface. The crew and local authorities responded quickly enough to stop the flooding from becoming total, and the ship was stabilized where she rested. A Navy rescue and salvage vessel was diverted from the Philippines, and a tugboat at Subic Bay received orders to sail for Saigon. Seventeen days later, the Card was refloated and towed to the Philippines for repair. What the Navy did not do was admit the truth. Officially, the Card had been merely damaged and quickly repaired. The U.S. military refused to acknowledge that a Viet Cong commando team had sunk an American ship at her own berth in a supposedly secure port. The distinction between damaged and sunk mattered enormously to an administration that was still trying to project confidence.
The Card returned to service on December 11, 1964, and continued hauling military equipment to Vietnam until 1970, when she was finally retired to the Reserve Fleet. But the attack's significance outlasted the ship's career. The sinking was one of the first major Viet Cong strikes against an American military asset, predating the Brinks Hotel bombing by seven months and the Gulf of Tonkin incident by just two. Together, these events marked 1964 as the year when the war stopped being an advisory mission and became something the United States could no longer keep at arm's length. In Saigon Port today, where container ships dock along the same stretch of river, there is little visible trace of the night two men crawled through a sewer with 80 kilograms of explosives and changed the calculus of a war.
Located at 10.765°N, 106.71°E along the Saigon River in Ho Chi Minh City. The port area sits on the western bank where the river curves through the city center. Nearest major airport is Tan Son Nhat International (VVTS), approximately 8 km northwest. From the air, the Saigon River's winding course through the urban landscape is clearly visible, with the port facilities along the waterfront. The Thu Thiem district across the river, where the commandos staged their approach, is now a modern development zone.