BIRMINGHAM, Ala. — When the Civil War was over, when the dead were buried and the union was reunited, it came time to tell tales and write history. In reunion gatherings and living rooms alike, differing versions of the causes of the conflict became as hardened as sunbaked Georgia clay.More than a century and a half later, those dueling narratives are with us still.Did 620,000 die, as Northerners would have it, in a noble quest to save the union and end slavery — the nation's horrific original sin? Or was the "War Between the States" a gallant crusade to limit federal power, with slavery playing a lesser part, as Southerners insisted?