Really cool piece, good handle on the orchestration and harmony (some of those chord progressions are pretty satisfying) - the audio rendering is also really cool, those sfs on the trombone chords for instance...
Something to consider is making the transitions a little tighter; some can be abrupt if the music calls for it (like the one going into the final section) but more 'build-up' or 'come down' before and after climactic sections might give the piece more flow. The ideas themselves are good and idiomatic, and you clearly have a good idea of what it is you want. Another note, my personal taste would be to give the horns less foreground time; they sound amazing, but they can definitely be overused, especially in epic settings with bombastic ideas like here.
Thanks for sharing!