I just watched Legends of the Fall which also takes place during The Great War period.
Legends of the Fall is a really great movie and James Horner did the incredible music score. You can hear the "Glory" in it as well as some western music influence.
The World War One sequence is done brilliantly and the movie traces the years 1913 - 1921 (mostly) and also covers Prohibition.
My own novel has some of this movie's feel to it.