I've loved "Glory" since the first time I saw it (in school one day as a history "assignment"). Initially, I didn't quite understand all of the details of why I enjoyed it so much, however. Obviously, one of the main reasons is this score, which is sometimes so subtle you don't realize it's there, but is at all times applying an influence. It may be to uplift you ("Jubilee"), make you sad ("Whipping"), courageous ("Fort Wagner"), or somber ("Epitaph"). I've shed a couple tears while watching the charge on Fort Wagner, and even listening to the music alone can almost stir the same level of emotion.
The orchestral parts are superb, but there is something particularly stirring about the use of the boys choir. Namely at the emotionally-charged climax, when we are confronted with the harsh results of their failed plans. The simple, innocent voices contrasting against that imagery is startling.
I'm not an ascribed fan of James Horner, but I do love a good soundtrack, and this one -- as far as I'm concerned -- ranks up with "Star Wars" and "Gladiator".