Attack on USNS Card

Despite their best efforts to control VC activities across the river in the Thu Thiem area, the South Vietnamese military and police could not stop VC agents from operating there. So VC members of the 65th Special Operations Group were able to watch US and South Vietnamese military activities at the port, while they were preparing to attack American targets. Lam Son Nao, a commando of the 65th Special Operations Group, was also an employee at the port facility.[4] As his unit was assigned with the mission to attack the carrier, Nao took advantage of his position as an employee at the port facility, to reconnoitre Card to design the best strategy to sabotage the ship and all the military hardware on board. Nao's father had previously worked at the port facility as a tradesman, so he memorized all the tunnels and sewage systems at the facility. He advised Nao that the best way to enter the area where American ships normally anchored was through the sewer tunnel opposite Thu Thiem.[4]

While bathing in the Saigon River, Nao inspected the sewer tunnel, which his father had advised him to use. Nao concluded that the tunnel would provide the best access to the American area, but it also presented challenges. The sewage tunnel contained waste and toxic oils which could cause blindness, so Nao and his men would have to close their eyes as they moved through it to avoid blindness.[5] Nao and his men must bathe to purge deadly odours to avoid detection, and probably arrest, by South Vietnamese authorities. After Nao had surveyed the tunnels leading to the port, he presented his plan to the Saigon-Gia Dinh Military District Headquarters. Nao decided to utilise high explosives, enough to sink a ship, and to detonate them using a timer so that his men could get away safely. Nao's superiors approved the plan and they ordered him to launch the attack before sunrise to avoid killing local Vietnamese civilians.[5]

Nao returned to Saigon and began assembling the equipment required for the attack, which included C4 plastic explosives, TNT, wire, mine detonators and batteries. Nao trained new commandos, namely Nguyen Phu Hung and Nguyen Van Cay, to support his operation. To ensure success, Nao measured the height, length and width of the sewer tunnel to assemble the bomb devices to the right size, to be carried through the tunnel unhindered.[5] Towards the end of 1963, Nao received news that Card had arrived in Saigon with another load of armored personnel carriers, artillery and aircraft. But the carrier turned out to be her sister ship, USNS Core. On the evening of December 29, 1963, Nao and Cay carried their bomb devices, which had about 80 kilograms (180 lb) of explosives, through the sewer tunnel. They attached the explosives to Core's hull, set the timer and retreated into the sewer to await the outcome.[5]

The bombs failed to explode because the battery had expired due to protracted storage.[5] Determined the operation would remain a secret, the commandos snuck back to Core and retrieved the explosive devices. Soon, Core and its crew sailed from Saigon without any damage. Nao reported the mission failure to the Saigon-Gia Dinh Military District Headquarters. His superiors did not express disappointment in the failure, but they encouraged Nao and his men to destroy Card at all costs. On May 1, 1964, Viet Cong reconnaissance teams spotted USNS Card as she sailed through Ganh Rai Bay and entered Long Tau River. They reported this information to the 65th Special Operations Group in Saigon.[6] As usual, Card docked at the commercial port to unload a shipment of cargo and military helicopters, and pick up helicopters to be returned to the US.[7]

When Nao received news Card had arrived in Saigon, he inspected the equipment which included a new battery and a redesigned bomb. Nao decided to set off the bombs during the early hours of May 2, so that he and his fellow operative could escape safely and avoid inflicting casualties on the local population. Due to illness, Cay declined to take part in the operation, so Hung had to replace him.[6] At around 9am on May 1, Nao rushed to Hung's home, where the latter was given a hand grenade and was notified of an upcoming operation without much detail. At 6pm, after Nao had finished loading the bombs onto one canoe, he and Hung traveled down the Saigon River in two separate canoes, toward the commercial port district. They pulled over in the Thu Thiem area. To avoid detection by South Vietnamese authorities they mingled with the local workers. While awaiting the right time, Nao briefed Hung on the objectives of the operation, which was to sink the largest American ship at the Saigon Port, and report the results to headquarters.[6]

Shortly after 6:30pm as both men headed toward Warehouse Number 0 at the commercial port, a police patrol boat spotted them and gave chase. Nao ordered Hung to throw the hand grenade and both men would retreat toward the local village if their bombs were discovered by police. The police patrol stopped about 20 meters (66 ft) away from Nao's canoe, and the patrol boat commander questioned both men about their activities during that evening.[8] Nao claimed that he and Hung intended to go to the other side of the river to buy new clothes at the market. To avoid delaying the operation, Nao bribed the patrol boat commander 1000 Vietnamese dong,[9] as the South Vietnamese police were widely known for their corruption. When the patrol boat commander received the bribe, he gave both Nao and Hung permission to move on but demanded another bribe when they return. When the commandos arrived at the sewer tunnel, they assembled the bomb device with each man carrying 40 kilograms (88 lb) of explosives through the tunnel.[8]

When the commandos emerged from the tunnel, they swam toward the broadside of Card which anchored near the sewer opening. Nao and Hung attached two bombs to the ship, with one near the bilge and one at the engine compartment, just above the waterline. Nao then inspected both bombs to ensure proper assembly.[10] Nao then stuck the battery onto a pole and connected it to the bombs with wires, then set the timer. At 1.10am, the bombs were completed and both commandos retreated to the sewer tunnel, boarded their canoes on the other side and rowed back to Thu Thiem. Again, the police patrol boat was waiting for Nao and Hung to arrive, because the commander wanted another bribe. As Nao and Hung approached the patrol boat, an explosion was heard and a bright light could be seen in the commercial port area. The South Vietnamese police patrol boat then started its engine and raced towards Card, instead of extracting another bribe.[10]