I'm also a fan of Glory and Gettysburg. To that, I think I'll also add:
https://www.imdb.com/title/tt0120815/
Cliched, but it is a pretty good movie.
https://www.imdb.com/title/tt0265086/
Also cliched, also good.
https://www.imdb.com/title/tt0243609/
A true story about four Allied POWs who...