Doug Hegdahl Seaman Apprentice ( E - 2 ) Douglas B . Hegdahl is a former United States Navy sailor who was a prisoner of war ( POW ) during the Vietnam War . After his early release by North Vietnam , upon returning to the United States , he was able to provide the names and personal information of about 256 other POWs as well as revealing the conditions in the prison camp . Prisoner of war . On April 6 , 1967 , 19 year old Doug Hegdahl was knocked overboard by the blast from a 5 - inch gun mount from the USS " Canberra " in the Gulf of Tonkin , three miles off the coast . He swam until he was picked up several hours later by Cambodian fishermen who treated him well . Trying to cover for him , his shipmates did not report him missing for two days , so the commanding officer did not know to look for him . Hegdahl was turned over to Vietnamese militia men who treated him less hospitably , clubbing him repeatedly with their rifles before moving him to the infamous " Hanoi Hilton " prison . The interrogators first insisted that Hegdahl was a commando or an agent . His story of being blown overboard seemed unbelievable to the interrogators . Hegdahl quickly realized he ' d be much better off if he pretended to be a lowly fool . Hegdahl was slapped around for a few days before convincing his captors that he was of little value to them . His bumpkin demeanor , youthful appearance , and country accent aided in his ability to convince them that he was no threat to them . He was given almost complete run of " the Plantation " , a satellite POW camp near the " Hilton " . When asked to write statements against the United States , he agreed , but pretended to be unable to read or write , which was believable to the Vietnamese captors . Thinking they had someone who would be easily turned to their cause , they assigned someone to teach Hegdahl to read . After Hedgahl appeared to be incapable of learning to read and write , his captors gave up on him . Later , he came to be known to the Vietnamese as " The Incredibly Stupid One " . Because they thought he was so stupid , the Vietnamese gave him nearly free rein of the camp . With the help of Joe Crecca , an U . S . Air Force officer and fellow prisoner , Hegdahl memorized names , capture dates , method of capture , and personal information of about 256 other prisoners — to the tune of a nursery rhyme " Old McDonald had a Farm " . Hegdahl is still able to repeat the information to this day . According to his senior officer and cellmate , Lieutenant Commander Richard A . Stratton , Hegdahl also convinced his captors that he needed new glasses and memorized the route from the prison into the city of Hanoi , where he was taken to be fitted . During his prison stay , Hegdahl sabotaged five trucks by putting small amounts of dirt in their gas tanks . After he was through with them , each of the vehicles had to be towed from the compound . Hegdahl was one of three POWs who were released from Hanoi on August 5 , 1969 as a propaganda move for the North Vietnamese . Although the POWs had agreed that none would accept early release — that they would all be released together — the POWs agreed that Hegdahl ' s release should be an exception . He was ordered by LtCmdr Stratton to accept an early release so that he could provide names of POWs being held by the North Vietnamese and reveal the conditions to which the prisoners were being subjected . After his discharge , Hegdahl was sent to the Paris Peace Talks in 1970 — and confronted the North Vietnamese with his first - hand information about the mistreatment of prisoners . Post - Vietnam . After returning to the U . S , Hegdahl used his experiences as an instructor at the United States Navy ' s SERE ( Survival , Evasion , Resistance and Escape ) school based in NAS North Island , San Diego , California .