Inner Strength By Communication allowed POWs to maintain strength and a sense of community. But talking or writing--any communication--was strictly against prison rules. The North Vietnamese, however, were never able to stop POW communication. This success marked an important victory for the prisoners. Sending Messages Tapping on walls was one way to send messages. The POWs' "tap code" used letters arranged in a grid. Each letter was signaled with taps--horizontal row first, then vertical. Abbreviations were common. For example, the question "When do you think we'll go home?" became WN DO U TK WE GO HOME. Taps 1 2 3 4 5 1 A B C D E 2 F G H I J 3 L M N O P 4 Q R S T U 5 V W X Y Z Keeping Mind and Body Fit Crushing boredom was a fact of life in North Vietnamese captivity. To keep their minds active, many POWs memorized the names of every prisoner in their camp, and repeated them every day so that none would be forgotten. Some worked out complex math problems in their heads, and others made detailed observations of insect behavior. Prayer sustained many prisoners. Late in the war, when POW treatment improved, prisoners taught one another languages and other skills--some learned enough to test out of university courses when they returned home. To stay fit, many POWs walked several miles each day in their tiny cells. Others did sit-ups and push-ups. Keeping a strict mental and physical routine helped the men pass the time and stay sharp. Click here to return to Return with Honor: American Prisoners of War in Southeast Asia.