Sixty years after the Civil War, the 121st New York Volunteers (Upton's Regulars) finally published a history of their regiment. Its stated author was a man who had not served directly with the 121st but had based the book on a memoir written by a survivor who had enlisted at age 15. That boy, Dewitt Clinton Beckwith, published his memoir thirty years after the war in an obscure upstate New York newspaper, The Mohawk Democrat. For years, the "origin story" lay in plain sight, until editor Salvatore Cilella discovered the memoir while performing research for a regimental history. The original...