Gods and Generals is a 2003 film based on the novel, Gods and Generals, by Jeffrey Shaara. It is considered a prequel to the 1993 film Gettysburg, which was based on The Killer Angels, a novel by Michael Shaara, Jeff Shaara's father.
The film stars Jeff Daniels as Lieutenant Colonel Joshua Chamberlain and Robert Duvall as Robert E. Lee. While many of the actors from Gettysburg reprised their roles for this film, Stephen Lang is one of a few to play a different character: George Pickett in Gettysburg and Stonewall Jackson in Gods and Generals. Martin Sheen, the original Lee, had conflicts due to the shooting schedule of The West Wing, and was replaced by Duvall.
It was directed by Ronald F. Maxwell, who had also previously directed Gettysburg in 1993. After the box office underperformance of Gettysburg, Maxwell was unable to get the prequel greenlit until media mogul Ted Turner provided the entire $60 million budget.
If you follow the link below you will notice this film was a critical and financial failure but it is still a very good film though not as good as Gettysburg...worth having though as a prequel to the much better Gettysburg.