Play Dirty (1969)
You almost have to see this anarchic, nasty, selfish, brutal WWII movie as a comment on Vietnam, and on war. It's 1969. At first you think Michael Caine, for all his talent, is miscast, but the odd displacement of his character among a lot of very hardened, serious men is part of what works.
This is not like any WWII you've seen. It's an odd mixture of hardship, tedium, humor, and straight up masculine grit. It's set in the Sahara, so dunes and sand and dry nasty weather rules. There is a mission at hand, and these men have to be unorthodox and ruthless to succeed. But there are long stretches of just traveling and conquering the desert, of going day after day through storms and lack of storms. There is also fighting amongst the men, a somewhat horrifying (and unnecessary) attempted rape, some bloody carnage of natives, and of Germans, a long twenty minutes of Fitzcarraldo heroics with some cables, and so on.
But in the end, it really does capture something essential of war, including the nonsense of some of it, and the lack of rules, and the lack of personal safety that comes from chaos, and the difficulty of companionship and trust.