I gotta recommend a movie I just watched: Ride with the Devil. Ang Lee film with Tobey Maguire in the lead. I Netflixed it after reading a book on the guerrilla campaigns in Kansas and Missouri in the Civil War and ended up, while doing further research, seeing this movie listed as an 'in popular culture' thing on Wiki.
Apparently it didn't see very wide release in the U.S...the reasons for this being many and varied, but one commonly referenced is that the studio didn't believe that a movie with a black guy fighting for the Confederates would sell well...of course the character in the movie was inspired by a real person...
Anyhow, it's a pretty good flick in the 'war drama' vein, and there's some decent attention to detail...the bushwhackers tend to carry multiple pistols rather than rifles, for example.