I definitely disagree that there are antiwar films, though some psychopath would take them and still think a film like Come and See or the new All Quiet on the Western Front are "based"; those films are very effective at demonstrating the ridiculous and horrifying realities of war. There's also films like Threads, which talk about the apocalypse of a nuclear war.

Also a shoutout to the user that recommended Generation: Kill which felt like the first real war series that I've been able to watch. Fuck Tom Hanks for making/producing The Pacific and Band of Brothers, lots of boring cutaway scenes and emotional manipulation to make you think that shooting surrendering people is good compared to whatever else happens in a war.