I haven't watched Gettysburg but I have watched the second film in the trilogy, Gods and Generals. This film is one of the most awful films I've seen in a long time. While they tried to make the battle scenes realistic, with mixed success (and they are to be commended for that), nothing else about the film is realistic. Was this a film about humans on Earth, or saints in Heaven? I couldn't tell. It was mostly a film of rousing speeches and stirring music. No matter how honourable, dignified and educated you think the US civil war generals were, there's no way they spoke and acted and communicated like the film depicts. People don't talk and interact like that today and they didn't talk and interact like that back then. People swear, spit, grunt, umm and ahh, they scheme, they politicise, they socialise, they laugh, they do good and evil.
This film is yet another example of the American tendency to canonise their historical figures, turn them into saints. It really is a process of dehumanisation. I think the only way the civil war film genre (mostly awful up till now) is going to be redeemed is if directors stop focusing on these "saints" and the famous battles, and start telling stories of the little guy in the war, the Johnny Rebs and Billy Yanks. But I'm skeptical of this ever happening. Too much has been invested in this civil war mythology.