Only joking
It's really Deer hunter as it deals with before during and after the war.
I would have said First Blood but the war only features in very small sections
Also Casualties of war with michael j fox was a very moving film for me
Apocalypse is highly overrated and one of the most boring movies I have ever seen IMO, same for Platoon. Although I have not seen Platoon in something like 10 years so I should probably give it another shot.
would have to watch both again, it's been so long. the one that comes to mind though is We Were Soldiers, rewatched it not long ago and DAMN it sure makes you think about what these brave men went through on the front lines.