Exterior filming took place primarily in Massachusetts and Georgia. Opening passages, meant to portray the Battle of Antietam, show volunteer military reenactors filmed at a major engagement at the Gettysburg battlefield. Zwick did not want to turn "Glory" "into a black story with a more commercially convenient white hero". Actor Morgan Freeman noted: "We didn't want this film to fall under that shadow. This is a picture about the 54th Regiment, not Colonel Shaw, but at the same time the two are inseparable". Zwick hired the writer Shelby Foote as a technical adviser, who later became widely known for his contributions to Ken Burns' PBS nine-episode documentary, "The Civil War" (1990).