Thirty 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 Hekrimer Democrat. For years, the "origin story" lay hidden in plain sight, until editor Salvatore Cilella discovered it while researching for a regimental history. The original 53 weekly installments, edited and annotated here, richly detail the horrors and folly of war. They reveal the slow maturation of a boy thrust into almost four years of war. Beckwith was present at nearly all the historic Eastern Theater engagements from Antietam to Appomattox, including an abortive stint with the 91st New York in Florida in 1861. He describes his various Tom Sawyer-like adventures with the VI Corps of the Army of the Potomac, dealing with death, disease, loss and ultimate elation at Lee's surrender, tempered only by Abraham Lincoln's death.