I will second, and add the subtitile in case the OP doesn’t know it, Mars: The Bringer of War.
You could then end with Venus: The Bringer of Peace.
I hope it’s not a nitpick to point out that “songs” have words. You probably don’t want songs, probably not even instrumental versions of songs.
It was composed for a movie about a different war (U.S.A. Civil War), but the music of Glory by James Horner is just great.
There are few pieces more epic than “The assault on Fort Wagner”
Marc Blitzstein wrote The Airborne Symphony in 1946 about WWII, but I think most of the twelve sections have words. “The Ballad of the Bombardier (Emily)” is one of the most moving things I’ve ever heard, though–it stopped the show at the Encores! Bash last November.
Another vote for Victory at Sea and Britten’s War Requiem.