Fort Sumter The Confederate bombardment that began the Civil War on April 12, 1861, lobbed more than 4,000 rounds at Fort Sumter. Shrapnel from thirty-three hours of cannon fire shredded this flag. When Union major Robert Anderson surrendered on April 13, he and his men marched out of the fort under this tattered banner. When Anderson returned in April 1865, he raised this very flag. Photograph: Minnesota Historical Society; flag: United Daughters of the Confederacy.