On May 20, 1938, a young man from the Bronx informs his parents that he is leaving for the Catskills to begin his new job as a waiter. Instead, he sails for Europe to join the Abraham Lincoln Brigade in the Spanish Civil War, the opening round in the fight against Hitler and Mussolini. The man, Dave Lipton--the author's uncle--sends letter after letter home detailing his hopes and begging for forgiveness. He never receives a reply. Decades later,...