Even as the 150th anniversary of the Civil War moves into its second year, Americans still disagree on what was the fundamental root cause of the war. But one author says it really was all about the moral question of slavery. Pewaukee writer, teacher, and independent Civil War historian Thomas Martin Sobottke is the author of the new book, Across That Dark River: The Civil War Memory. It's published by Moving Train Books LLC, which he also founded. He spoke with Stephanie Lecci. You can hear about the origin for Sobottke's book title as supplemental audio below.