For those who have not seen it, Journey's End (2017) is a very effective war movie. I would compare it to Dunkirk, although the pace is a little less exciting. It is more of a personal drama about war.
The movie is based on a 1928 play about World War 1. Almost the entire movie takes places in the trenches, just prior to the German "Spring Offensive" in 1918.
There have also been three other movies based upon this play, first in 1930, and a German version in 1931, and the 1978 "Aces High" where the story was changed to be about fighter pilots.