It was the deadliest maritime disaster in the history of the United States, the sinking of the S.S. Sultana right after the end of the Civil War. And yet, no one was ever convicted of a crime, despite evidence of gross negligence. Larry Potash profiles a man with a personal connection to the tragedy, and a remarkable discovery he's made about his ancestor.  Backstory airs Sunday nights at 6:30 & 11 on WGN, or stream it anytime on the WGN+ app on your smart TV with Amazon Fire, Roku, and Apple TV. Check out the Backstory podcast at WGNtv.com/Backstory via Apple Podcasts, Google Play, or wherever you get your podcasts.