(Commentary by Gary Gallagher, professor emeritus of history) Ken Burns’ documentary on the Civil War has reached a larger audience and generated more interest in the subject than any book, theatrical film, or other influence in the past 50 years. First broadcast on PBS stations in 1990 and frequently re-aired ever since, it also appeared in a digitally restored 25th anniversary version with additional material of various kinds. Most viewers have responded positively to the series, though they often disagree about such things as Burns’ relative treatment of the Union and the Confederacy, the d...