"In 1873, four years before what historians consider the official end of Reconstruction, Mark Twain wrote that the Civil War era already had become a historical perennial. "History," Twain wrote, "is never done with inquiring of these years, and summoning witnesses about them and trying to understand their significance." The nine years between South Carolina's secession in 1860 and the election of Ulysses S. Grant as president in 1868 signified a watershed in American history. Twain recalled tha...