A book you might want to check out on this particular topic is Gary Gallagher Causes Won, Lost, and Forgotten: How Hollywood and Popular Art Shape What We Know about the Civil War. A significant portion of his book involves trying to define particular strains of memory (lost cause, emancipation, post-Vietnam loss of heroism) and how these particular memories impact how cinema portrays the war and the ultimate meaning of the war for narrative purposes. These shifts in historical presentation and narrative often reflect the zeitgeist very well. For example, since the Civil Rights Movement, the emancipationist memory has been one of the default narrative of a typical Civil War film. Even a very sympathetic pro-Confederate film like Gods and Generals portrays the CSA's officers as realizing that slavery must be abolished to retain a pretense of morality, which is a concern not evident in earlier films like Gone with the Wind. Both films are dipping deep into the well of the Lost Cause, but their respective historical contexts (1939/2003) shape how they package it.

If you're interested, Gallagher did a presentation at CSPAN2's Book TV that's rather amusing and was on a panel which goes into the legacy of the war and discusses the difference between memory and history.