Three sentence AI summary: Dorence Atwater, an 18-year-old Union soldier imprisoned at Andersonville, secretly copied the camp’s death register, risking execution to preserve the identities of roughly 13,000 fallen prisoners. After the war, he and Clara Barton used his hidden list to identify and mark the graves, giving thousands of families long-denied answers. Though he was court-martialed for refusing to surrender the list, Atwater was ultimately vindicated, publishing the names and later building a distinguished life abroad as a respected U.S. consul and Tahitian citizen.