Attack on the USNS Card The Attack on the USNS " Card " was a Viet Cong operation during the Vietnam War . It took place in the port of Saigon in the early hours of May 2 , 1964 , and mounted by commandos from the 65th Special Operations Group . The " Card " was first commissioned into the United States Navy during World War II , playing a significant role in destroying German Navy submarines as the flagship of Task Group 21 . 14 . Decommissioned in 1945 , the " Card " was reactivated in 1958 and entered service with the Military Sea Transport Service , transporting military equipment to South Vietnam as part of the United States military commitment to that country . With the USNS " Card " a regular visitor to the port , it became a target for local Viet Cong commando units . Shortly after midnight on May 2 , 1964 , two Viet Cong commandos climbed out of the sewer tunnel near the area where the " Card " was anchored , and they attached two loads of explosives to the ship ’ s hull . The attack was a success and the " Card " sank 48 feet , and five civilian crew members were killed by the explosions . The ship was refloated 17 days later , and was towed to the Philippines for repairs . Background . The USNS " Card " was a Bogue class escort carrier that had served in the United States Navy with distinction . The " Card " ’ s hull was laid down on October 27 , 1941 ; originally intended as a cargo ship , the ship was reclassified ACV - 11 and converted into an escort carrier with a displacement of 9 , 800 tons . On July 15 , 1943 , the " Card " was reclassified CVE - 11 and became the flagship of Task Group 21 . 14 ( TG21 . 14 ) , a hunter - killer group formed to destroy German submarines in the North Atlantic . During the periods between July and November , the " Card " ’ s aircraft and the escort vessels of TG21 . 14 destroyed a total of five German submarines . On November 11 , 1943 , the " Card " and her escort destroyers were awarded the Presidential Unit Citation for their success as part of TG21 . 14 , and the " Card " became the first escort carrier to receive such an award for combating German submarines . By the end of World War II , the " Card " and her aircraft destroyed a total of 11 German submarines , which made it the second most successful ship of its class . After 1945 the " Card " was decommissioned and briefly put out of service when it was transferred to the Atlantic Reserve Fleet . On May 16 , 1958 , the " Card " re - entered service with the Military Sea Transport Service , under the control of the United States Navy . The ship was manned by a civilian crew and was prefixed " USNS " ( United States Naval Ship ) instead of " USS " ( United States Ship ) as it was in service but not commissioned . With the war ' s escalation , the United States government stepped up military support for South Vietnam ' s fight against the Communist National Liberation Front ( also known as the Viet Cong ) . On December 15 , 1961 , the USNS " Card " left Quonset Point , Rhode Island , with a cargo of H - 21 Shawnee helicopters and U . S . soldiers from Fort Devens , Massachusetts , bound for Vietnam . At Subic Bay in the Phillipines , the cargo and troops were transferred to the " USS Princeton " , which arrived and unloaded off the coast of Da Nang the following month . From 1961 onwards , the " Card " and the USNS " Core " regularly docked in Saigon to unload heavy artillery , M - 113 armored personnel carriers , aircraft , helicopters and ammunition for the South Vietnamese government . The Port of Saigon was situated between the Te and Ben Nghe Canals , and was about wide from one side to the other . To facilitate the arrival of the " Card " and other American ships which pulled into Saigon , the South Vietnamese military often deployed navy vessels to conduct patrols around the port , while the surrounding shores were protected by an elite Army of the Republic of Vietnam ( " ARVN " ) airborne battalion . The port itself was guarded round the clock by South Vietnamese police , as undercover South Vietnamese agents operated across the river in the Thu Thiem area to disrupt Viet Cong activities there . Undeterred by the level of protection which the South Vietnamese government normally afforded to American ships , Tran Hai Phung — commander of the Viet Cong ’ s Saigon - Gia Dinh Military District — ordered the 65th Special Operations Group to attack the USNS " Card " . Sinking of the USNS " Card " . Failed attempt on the USNS " Core " . Despite their best efforts to control Viet Cong activities across the river in the Thu Thiem area , the South Vietnamese military and police could not stop Viet Cong agents from operating there . So Viet Cong members of the 65th Special Operations Group were able to watch U . S . 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 . As his unit was assigned with the mission to attack the American escort carrier , Nao took advantage of his position as an employee at the port facility , to reconnoitre the " 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 memorised all the underground tunnels and sewerage systems which ran in and out of the facility . He advised Nao that the best way to enter the area where the American ships normally anchored , was via the sewer tunnel opposite Thu Thiem . On one occasion while he was bathing in the Saigon River , Nao decided to inspect the sewer tunnel which his father had advised him to use . Nao concluded that the tunnel would provide the best way to get in and out of the American area , but using it also presented challenges . The sewerage tunnel contained both wastes and toxic oils which could cause blindness , so Nao and his men would have to close their eyes as they move through the tunnel , in order to avoid blindness . Furthermore , Nao and his men must wash their bodies to get rid of the deadly odours to avoid detection , and probably arrest , by South Vietnamese authorities . After Nao had surveyed the tunnels which lead into the port , he presented his plan of attack to the Saigon - Gia Dinh Military District Headquarters . Nao decided to utilise high explosives , enough to sink a ship , and detonate it 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 . Nao then returned to Saigon and began assembling the equipment required for the attack which included C4 plastic explosives , TNT , wires , mine detonators and batteries . Nao also trained new commandos , namely Nguyen Phu Hung and Nguyen Van Cay , to support his operation . To ensure that his operation would go smoothly , Nao measured the height , length and width of the sewer tunnel to assemble the bomb devices to the right size , so it could be carried through the tunnel unhindered . Towards the end of 1963 , Nao received news that the " Card " had arrived in Saigon with another load of armoured personnel carriers , artillery and aircraft . But the aircraft carrier turned out to be the sister - ship the USNS " Core " . On the evening of December 29 , 1963 , Nao and Cay managed to carry their bomb devices through the sewer tunnel which had about of explosives . The commandos attached the explosives to " Core " ’ s hull , set the timer and retreated back into the sewer to wait for the outcome . However , the bombs failed to explode as planned , because the battery had expired due to long periods of storage . Determined the operation would remain a secret , the commandos snuck back to the " Core " and retrieved the explosive devices . Not long afterwards , the " Core " and its crew sailed out of Saigon , intact without any damage . Nao , on the other hand , reported the failure of his mission to the Saigon - Gia Dinh Military District Headquarters ; his superiors did not express disappointment in the failure of the operation , but instead they encouraged Nao and his men to destroy the " Card " at all costs . Finally on May 1 , 1964 , Viet Cong reconnaissance teams spotted the USNS " Card " sailed through Ganh Rai Bay and entered Long Tau River , so they immediately reported the information to the 65th Special Operations Group in Saigon . As usual , the " Card " docked at the commercial port district in the city to unload another shipment of cargo and military helicopters , as well as upload a batch of helicopters scheduled to be returned to the United States . Successful attack . When Nao received news the " Card " had arrived in Saigon , he inspected the equipment which now included a new battery and a redesigned bomb . Again , 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 . But due to illness , Cay declined to take part in the operation , so Hung had to replace him . 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 unloading the bombs onto one canoe , he and Hung traveled down the Saigon River in two separate canoes , towards the commercial port district . Both men than pulled over in the Thu Thiem area , to avoid detection from South Vietnamese authorities by intermingling with the local workers who lived there . While waiting for 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 promptly report the results back to headquarters . Shortly after 6 : 30pm as both men headed towards Warehouse Number 0 at the commercial port district , a police patrol boat spotted them and quickly gave chase . Nao than ordered Hung to throw the hand grenade and both men would retreat towards the local village , if their bombs were discovered by the police . The police patrol stopped about away from Nao ’ s canoe , and the patrol boat commander questioned both men about their activities during that time of the evening . In response , Nao claimed that he and Hung intended to go to the other side of the river , to buy some new clothes at the market . To avoid delaying the operation , Nao decided to bribe the patrol boat commander , 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 of explosives down through the tunnel . Once the commandos finally got out of the tunnel , they both swam towards the broadside of the " Card " which anchored near the opening of the sewer . As planned , Nao and Hung attached two bombs on the ship , with one near the bilge and one at the engine compartment , just above the water surface . After the bombs had been attached to the " Card " ’ s hull , Nao inspected both bombs to ensure they had been assembled properly . After that Nao stuck the battery onto a pole and connected it to the bombs with wires , than set the timer . At 1 . 10am , the bombs were completed and both commandos retreated back into the sewer tunnel , and climbed into 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 than started its engine and raced towards the " Card " , instead of extracting another bribe . Aftermath . For the Viet Cong commandos of the 65th Special Operations Group , the explosion on the " Card " signalled a successful mission . By the time the sun rose over Saigon , the " Card " had sunk into the river with its engine compartment completely flooded . Furthermore , five American civilians who worked on the ship died as a result of the attack . Due to the rapid response from the ship ’ s crew and the local authorities , flooding inside the ship was quickly stopped and it was stabilized . An inspection later revealed that the explosion had torn open a hole which measured long and high , on the starboard side of the ship . In the days that followed , five U . S . Navy divers were deployed to Saigon from the Philippines , in addition to several salvage teams from U . S . bases in Japan and the Military Sea Transport Service Command . The " USS Reclaimer " rescue and salvage ship , which was heading for the Philippines at the time , was ordered to change course and sailed for Saigon . Meanwhile , the tug boat " USS Tawakoni " based at Subic Bay in the Philippines was placed on standby , and later received similar orders to head for South Vietnam . Upon their arrival in Saigon , U . S . Navy divers and salvage teams tried to pump water out from the " Card " ’ s flooded compartments , but their initial attempts were hindered by a combination of malfunctions in the pumping equipment , and the poor diving conditions in the river . Ultimately it took the salvors 17 days to refloat the " Card " , and when that was completed they began the process of moving the ship out of Saigon by installing a 6 - inch pump and a load of generators inside the " Card " to get rid of excess water while at sea . The " Reclaimer " and the " Tawakoni " than towed the damaged " Card " out of Saigon , and headed for Subic Bay where it underwent further repairs . Shortly after the " Card " was sunk , North Vietnam made full use of the incident for propaganda purposes . On October 20 , 1964 , the North Vietnamese government issued a postage stamp which proclaimed an " " Aircraft Carrier of America sunk in the Harbor of Saigon " " , to praise the Viet Cong commandos who carried out the attack . The U . S . Navy refused to admit the " Card " had been sunk even for a brief period of time , instead it simply stated the " Card " was damaged and quickly repaired . For the remainder of 1964 , the Viet Cong launched further attacks on U . S . targets such as the Brinks Hotel and Bien Hoa Air Base , but again there were no significant responses from the U . S . military . The " Card " was returned to service by 11 December 1964 and remained in service until 1970 when it was placed into the Reserve Fleet .