There was a stellar dio posted or linked to on here a few months ago that I believe was based on a korean korean war movie. Browsing through the video store I came across Tae Guk Gi and it looked familiar, and I think this was the movie.

A good plot- about a couple of brothers who are drafted and get caught up in the war. There are several battle scenes and they're some of the best I've ever seen. I'm not sure on accuracy, but it looks amazing. Its in Korean, so you'll have to contend with subtitles if you don't speak the language, but the translation doesn't detract from the story (didn't for me at least). If nothing else, its worth a look for the battle scenes.