This is a really nice article about anti-war themes in Studio Ghibli films:
No film has ever made me cry so much as Grave of the Fireflies. From about 5 minutes into it until about an hour after it I was just bawling my eyes out. Even just reading that article has made my eyes well up again.
I really want to watch all the Ghibli films again now but maybe not Grave of the Fireflies, that would be too much…