When her neighbor handed her a stack of yellowed letters that had been rescued from an Atlanta, Georgia, trash pile, author Elizabeth Whitley Roberson had no idea she was about to embark on a fact-finding mission through six states, from Civil War battlegrounds in Pennsylvania, Maryland, and Virginia to Gwinnett County in North Georgia. The author of these letters was a young man named Eli Pinson Landers, a Confederate soldier in the Civil War...