They used to have a really cool physical version of this at the old visitor's center. It was in a little theater, and a narrator would walk the audience through the battle. You can see pics here: https://www.google.com/search?q=gettysburg+electric+map&tbm=isch&tbo=u&source=univ&sa=X&ei=_1_UUY7rPNXI4AP8zoGICg&ved=0CD0QsAQ&biw=1042&bih=895
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