--- title: "This future Medal of Honor recipient started a spy ring while held in Hanoi Hilton" description: "Two sonic booms told the American prisoners in Vietnam's infamous Hoa Lo prison – the Hanoi Hilton – their escape plan was a 'go.'" date: "2022-04-13" modified: "2023-04-11" authors: - name: "Blake Stilwell" job_title: "Editor-In-Chief, Air Force Veteran" link: "https://www.wearethemighty.com/authors/blake/" url: "https://www.wearethemighty.com/mighty-history/hanoi-prison-pow-escape/" categories: - "History" - "Vietnam War" - "War History" tags: - "Military History" - "Vietnam War" --- # This future Medal of Honor recipient started a spy ring while held in Hanoi Hilton ![]() [Two sonic booms told the American prisoners]() in Vietnam's infamous Hoa Lo prison – the Hanoi Hilton – that their escape plan was a 'go.' On May 2 and 4, 1972, two [SR-71 Blackbirds]() overflew Hanoi, North Vietnam at noon. The first plane broke the sound barrier, causing an ear-splitting sonic boom over the city. Fifteen seconds later, the other Blackbird did the same thing. Prisoners at Hoa Lo developed a code-tapping language to communicate with each other. Capt. James Stockdale, who was the senior ranking officer at the prison, taught many incoming POWs this code. It [kept the men]()[ sane and their spirits up](). Communicating with Washington was trickier. Three months into his captivity, Stockdale was allowed to write to his wife, Sybil. Two months later, he was allowed to write again. When she received the letters, she found them confusing. Nicknames and references to their mutual friends were wrong. Sybil gave the letters to Naval Intelligence in San Diego, who figured out that he was using doublespeak – deliberately misleading language – to let his superiors know he was not being treated well in North Vietnam. With her cooperation, the [CIA and Office of Naval Intelligence]() decided to use her correspondence with her husband as a way to communicate with the prisoners. Her first letter included a Polaroid of her with a secret message sandwiched between the sheets of photographic paper. It explained the process of using invisible ink to send messages to the CIA. He listed the other POWs with him and detailed the abuses inflicted on American prisoners there. ![ Stockdale climbing out of an F-8 before his capture (Photo by Stockdale Center) ]() *Stockdale climbing out of an F-8 before his capture. (Stockdale Center)* The new communication policy allowed the prisoners and the CIA to trade a wealth of information, so much so that the prisoners were actually able to assemble a small shortwave radio, which was eventually discovered during an inspection. In 1969, two prisoners, Air Force Captains John Dramesi and Edwin Atterberry, escaped from the prison at Cu Loc but were recaptured the next day. Massive reprisals from their captors followed, and thus the prisoners' leadership determined that the retribution was too much and escape attempts should only be made with a "[high likelihood of success and assurance of outside assistance." That's when they devised]() the Red River plan. ![Stockdale as a POW]() *Stockdale in captivity. (Department of Defense)* Members of the escaping POW group sent their plan to the U.S. Defense Secretary Melvin Laird, who approved the plan in January 1972. By May, everything was in place. The sonic booms were a go. Despite a few setbacks, members of SEAL Team One and [Underwater Demolition Team Eleven]() used SEAL Delivery Vehicles (SDV – mini-submarines) and HH-3A helicopters to patrol the coastline throughout May and June, looking for escaped POWs. They never found any. As the senior ranking officer, Stockdale forbade any escape attempts. He judged the plan too risky and the threat of reprisals too harsh (prisoners were often killed during these reprisals). The would-be escapees were frustrated by the policy, but they obeyed. Article III of the Code of Conduct for prisoners does say American POWs should make every effort to escape captivity. Article IV, however, prohibits any action that would cause harm to other captured personnel. So *Thunderhead* was terminated. The POWs would communicate with Washington throughout the war. Eventually, another radio was smuggled in, which gave POWs a direct line from the camp to the U.S. Seventh Fleet commanders aboard ships in the Gulf of Tonkin. ![ American POWs held in Vietnam being returned to U.S. military control at Gia Lam airfield, Hanoi. In foreground facing camera is USAF Capt. Robert Parsels. (U.S. Air Force photo)]() *American POWs held in Vietnam are being returned to U.S. military control at Gia Lam airfield, Hanoi. In the foreground, facing the camera is USAF Capt. Robert Parsels. (U.S. Air Force)* In January 1973, 591 POWs were repatriated to the United States. For his leadership among the prisoners and work to galvanize the resistance to their captors, Stockdale received the Medal of Honor from President Gerald Ford. ## Author Blake Stilwell is We Are The Mighty's Editor-in-Chief, covering military news, entertainment, and history, along with veteran education, employment and entrepreneurship. He is a former U.S. Air Force combat cameraman with degrees in Graphic Design, Television and Film, International Relations, Public Relations, Business Management and Middle Eastern Affairs. After leaving the military, he began working in film and television production in New York and Los Angeles, work that included ABC News, NBC Olympics, and HBO Sports. He then spent two years in Washington with White House Communications, before joining the Near East Foundation. At NEF he served as an International Development Fellow, then Communications Officer, and finally, Media Officer for the Middle East and Africa. Based in the Palestinian Territory, he coordinated strategic communications between eight country offices, international media, and government and NGO partners. He began a career focused on writing and editing in 2015 with We Are The Mighty. He left in 2019 for Military.com, but returned as Editor-in-Chief in 2025. Blake’s work has been seen on CBS News, Fox News, CBC, The Chicago Tribune, Task & Purpose, Military Times, Recoil, Skillset, American History, and was shockingly even used in a Supreme Court argument. He is an avid traveler and small business owner in Ohio, where he spends most of his energy fixing up a very old house. ### Author social links [Facebook]() [Twitter]() [Instagram]() [LinkedIn]()