Profile of retired Col. Carlyle Harris, a former POW in Vietnam who is credited with introducing the tap code, which the prisoners used to communicate. (U.S. Air Force Video // Jimmy D. Shea)


Questions consumed Capt. Carlyle S. “Smitty” Harris’ mind in the early days of his eight years as a prisoner of war in North Vietnam.

Harris’ thoughts focused mostly on his pregnant wife and two children back home near Kadena Air Force Base in Okinawa, Japan. Harris also wondered how the POWs could maintain any semblance of leadership and morale without a way to communicate with each other.

For eight long years of captivity, the questions lingered and gnawed at his mind.

Within five months after he’d joined the 67th Tactical Fighter Squadron in Thailand, Harris launched his second F-105 Thunderchief mission on Thanh Hoa Bridge April 4, 1965. After Harris hit his target, his F-105 was hit by anti-aircraft fire, and he was forced to eject. About 20 people from a nearby village immediately captured the pilot, and he was quickly surrounded by almost 50 villagers armed with hoes, shovels and rifles. Just as he was about to be shot, an elderly man stepped in because of the government’s orders to capture American pilots alive. Harris remained in captivity for 2,871 days, much of it at the Hoa Lo Prison, which POWs nicknamed the Hanoi Hilton.

After Louise Harris learned her husband was missing, she remained at their home in Okinawa with their two young daughters, Robin and Carolyn, until after their son Lyle was born. Six weeks after Lyle’s birth, she took her family to Tupelo, Mississippi, where her sister lived. Even before she received her first letter from her husband from Vietnam, Louise believed he was alive and made certain the children kept the faith, too. As Lyle grew older, he’d tell his mother, “There goes Daddy,” when an airplane flew overhead.

Shortly after his capture, Harris was placed in a cell in the Hoa Lo Prison, also known as the “Hanoi Hilton,”with four other POWs, and, at that time, he remembered a conversation with an instructor at his survival school training. The instructor had told him about a tap code Royal Air Force POWs used during World War II, and Harris taught the other four POWs the code. Their captors put them back in solitary confinement a few days later, but that only helped them spread the code throughout the seven-cell area, and ultimately, to POWs throughout North Vietnam.

“As we were moved to other camps away from Hanoi, someone always took the tap code with them and was able to pass it on,” said Harris, who retired from the Air Force as a colonel in 1979 and spent the next 18 years working in business, law and marketing in Mississippi. “So no matter where you went in the POW system in North Vietnam, if you heard a tap, the guy on the other side of the wall would respond with two knocks in return, and you’ve started the communication process.”

At the Hanoi Hilton and other POW camps in Vietnam, the tap code was not only a means to communicate with each other, but it also became a lifeline. In the code, the alphabet was arranged on a grid of five rows and five columns without the letter K, which was substituted with C. The first set of taps indicated which row the letter was on, and the second represented the column. So one tap followed by another tap meant the letter A, and a tap followed by two taps indicated B.

As soon as a POW returned from interrogation, he would begin tapping the wall to communicate what happened. When a prisoner returned from a particularly brutal interrogation, as soon as the guard turned the key and left the block, he’d hear a series of taps that communicated three letters: G, B and U for “God bless you.”

When Harris was being interrogated, for strength to resist demands for information, he thought back to his squadron commander in the 67th TS, Lt. Col. James R. Risner.

“While I was being interrogated the first couple of weeks, when it was pretty darned intense, I thought so much about Robbie Risner,” Harris said. “Mentally, I put Robbie Risner on a stool right beside me. It was my greatest effort to not do or say anything that he would not approve of. That really helped me.”

Risner was later captured, and confirmed the birth of Harris’ son after another POW first relayed the news through the tap code.

As the U.S. began its withdrawal from Vietnam, almost 600 POWs returned home in 1973, and Harris was finally released on Feb. 12. As he looked forward to his reunion with his family at Maxwell Air Force Base, Alabama, one question remained in his mind: the reception with his children after eight years of captivity, especially the 8-year-old son he’d never met.

When Harris stepped into the quarters where his family was waiting, Robin and Carolyn squealed and ran to his arms. “Oh, thank you, Lord,” he said, “they haven’t forgotten.” But when he saw Lyle for the first time, his son didn’t hug him back. However, about a half-hour later, as his father opened his arms, Lyle ran across the room and fell into his embrace.

After eight years, Harris had the answers to all of his questions.