Yes! Grave of the fireflies.
On my list also Waltz with Bashir and Levanon, both Israeli films. And No man’s land, about Yugoslavia.
A lot of my faves have been mentioned, but:
Saving Private Ryan
Kingdom of Heaven
Apocalypse Now
Bullet in the Head (the John Woo film, not the Stallone trash pile)
Centurion
1917
Full Metal Jacket
And can I cast a vote against The Deer Hunter? I’ve always thought it was the most overrated, nonsensical, inexplicable Best Picture winner ever.
Not even close for my vote. That goes to The Odd Angry Shot and The Boys In Company C. If you insist on voting Kubrick then Paths of Glory is the way to go.
That was one I should have mentioned in my post. Gripping series. As a bit sort of a technical “rivet counter” myself, I was also impressed with the degree of accuracy the producers strove for in the hardware and whatnot. ( weapons, vehicles etc )
My exact feelings as well. I’m glad you said it first as I didn’t want to be the first to be pummeled for it. 
It was loosely based on John Bulkeley. There was also an added feeling of realism because Robert Montgomery was a PT boat captain during WWII.
Two other good movies based on actual events:
I admit to being a Band of Brothers fanatic. I can’t say how many times I have watched it. I tend to think of all of the actors in it as “that guy from Band of Brothers” including Tom Hardy, Michael Fassbender and James McAvoy. I have read the book several times and several of the books written after by others. I met one of the main people in it once. So yes I highly recommend it.
Surprised these two haven’t been mentioned yet:
Me too! In so many cases, the actors in it were the first I’ve ever seen them in film/TV. subsequent watching of various films/TV really seemed to bring out the ‘Baader-Meinhof’ illusion. For example, I’d see Ron Livingston in ‘Office Space’ or ‘Swingers’ and my mind blurts out “Look, it’s ‘Nix’!”
I would nominate Oh, What a Lovely War as my personal favourite WW1 film. It’s a musical satire based on a stage play, but is well done and the “soldier” scenes are very authentic. The fourth Blackadder series, with Blackadder as a WW1 infantry officer in the trenches, is Rowan Atkinson funny (and with Hugh Laurie as a fellow officer), but the end of the last episode is astoundingly powerful!
Great movie subject, but the cheesy love story and crappy editing ruin it hard. I’d love to see a ‘serious’ remake of this, sticking as close to the truth as possible with no sap.
I so agree with these two comments. You can turn Private Ryan off after the landing. The rest is crap. Deer Hunter? My God, what a tedious movie. That wedding scene goes on longer than a lot of marriages!
Count me in with those comments as well.
A good, straight movie of Midway would now be possible. CGI can do wonders if you keep it away from the Michael Bay types. That would get rid of the thing that drove me crazy about the first one - the reliance on existing footage meant that the “hero” took off in one type of plane, attacked the Japanese is another type and crashed on the carrier upon landing in a third type.
You guys know they made another Midway movie just two years ago, right?
It’s not great.
That’s what I’d heard. That’s why they need to do it again, but get it right!
Have we mentioned Dr.Strangelove or Fail Safe (the original) yet? If we extend “war” to mean the Cold War then these have to be on the list.
The only nit I have to pick with Fail Safe is Dom Deluise as the whiny Air Force sergeant. The exact opposite of the character in the book. 
Lots of good films mentioned; if I had to vote for the very best, Apocalypse Now would be a contender. Incidentally the last time I watched it, it struck me as being a very dark comedy, anyone else agree?
It’s been a while since I have seen it but the Longest Day deserves to be mentioned because it does a great job of showing both sides ,which is relatively rare in war films, and also nicely shows military leaders working their way through the fog of war.
Grave of the Fireflies, Guns of Navarone and Master and Commander are some other films of high quality.
Two films that I don’t think have been mentioned: The Battle of Algiers arguably the best ever film on terrorism and counter-terrorism and 13 Days about the Cuban Missile Crisis.
I am happy for the commercial success of Dunkirk and 1917 (both of which I liked) and hope it paves the way for more war films; in particular I would like to see a really good Battle of Britain film on Imax 3D.
The 1969 movie was impressive. It was filmed largely with Luftwaffe aircraft then operated by the Spanish air force, something probably not possible today. Ron Goodwin’s score is great too.
I’m pretty sure I’ve seen that one, and you are right. As it happens, however, I have a personal problem with Japanese “us poor victims” war movies that I won’t bore you with here.