Far from home and training for World War II, American recruits in basic training turned to humor and correspondence to cope with the challenges they faced. In one letter home a young man described the vaccination process with wonderful exaggeration: “Two medical officers chased us with harpoons. They grabbed us and pinned us to the floor and stuck one in each arm.”

Yet one soldier began to realize that humor could only take him so far. Then he received a Bible. “I enjoy it very much and I read it every night,” he wrote. “I never realized you could learn so…