American history has always been an irresistible source of inspiration for filmmakers, and today, for good or ill, most Americans'sense of the past likely comes more from Hollywood than from the works of historians. In important films such as The Birth of a Nation (1915), Roots (1977), Apocalypse Now (1979), and Saving Private Ryan (1998), how much is entertainment and how much is rooted in historical fact? In The Columbia Companion to American History...