Turner's Gettysburg is useful since it does adhere, with some level of
accuracy, to the events surrounding the battle. there is some debate over
Martian Sheen's rendering of Lee as a very philosophical figure in the face of
battle, but this stems from the fact that we actually know very little of Lee
as a person, since his mythical persona has overshadowed everything else.
In terms of casting, Jeff Daniels is the best as Maine Col. Chamberlin. The
battle for Little Round Top is captured quite well, and is in fact (in my
view) the highpoint of the film. As a film for a history class, it would serve
as a good introduction to Gettysburg, or as an example of Civil War Battles.
Another good choice is Glory (1989?)-Drew