The Tap Code
One of the most important parts of a POW's life was communicating with his fellow captives. The first communication between isolated prisoners of war may have been a name scrawled on a piece of toilet paper with the burnt end of a matchstick. Notes and whispers were attempted, but both were often detected and severely punished.
In June 1965, four POWs — Captain Carlyle ("Smitty") Harris, Lieutenant Phillip Butler, Lieutenant Robert Peel and Lieutenant Commander Robert Shumaker — who were imprisoned in the same cell in Hoa Lo devised a simple, secretive code. The four men, expecting to be split up again, vowed to continue their resistance. To do so, they knew communicating closely would be essential.
Harris remembered an Air Force instructor who had shown him a secret code based on a five-by-five alphabet matrix. Each letter was communicated by tapping two numbers: the first designated the horizontal row and the second designated the vertical row. The letter W, for example, would be 5-2; the letter H would be 2-3. The letter x was used to break up sentences and the letter "c" replaced the letter "k." (One of the famous, yet inelegant, usages of the letter "c" for "k" was in the transmission "Joan Baez Succs," which POWs sent around the camp after the American anti-war activist's songs were played over the camp's public address system.) Here is the way the alphabet cpde was set up.
The guards separated the four prisoners after one was caught passing a note, and thus inadvertently spread the code, as the separated men taught it to others. By August 1965, most of the prisoners had been initiated, and were passing messages by tapping on the walls to fellow prisoners. "The building sounded like a den of runaway woodpeckers," recalled POW Ron Bliss.
Stockdale also talks of the pleasures of coming up with abbreviations, a necessity imposed by the time constraints on both the message giver and receiver. "Passing on abbreviations like conundrums got to be a kind of game," remembered Stockdale. "What would ST mean right after GN? 'Sleep tight,' of course. And DLTBBB? I laughed to think what our friends back home would think of us two old fighter pilots [Stockdale refers to Air Force Major Samuel Johnson, in an adjoining cell] standing at a wall, checking for shadows under the door, pecking out a final message for the day with our fingernails: 'Don't let the bedbugs bite.'"POW Vice Admiral James Stockdale, recalling the code in the book he wrote with his wife Sybil, In Love and War, recalls sending the code: "Our tapping ceased to be just an exchange of letters and words; it became conversation. Elation, sadness, humor, sarcasm, excitement, depression — all came through."
Some of the acronyms entered POW popular usage. One acronym, GBU, was used as a universal sign-off. It was shorthand for "God Bless You."