On April 26, 1865, on a wharf at Helena, Ark., photographer Thomas W. Bankes captured the steamboat Sultana packed with about 2,130 souls—almost 2,000 of them Union ex-prisoners-of-war. Soon, about 1,200 of them would be dead. One of the survivors, Corp. Erastus Winters of the 50th Ohio Infantry, tells the story.