Le ragazze di Okinawa

At the start of the Battle of Okinawa, a girl's school is hastily disbanded. The teachers and students find themselves in the battle as "the Lily Princesses Student Corps", working as nurses to the dying soldiers, under fire from American ships, and fleeing in shrinking groups of the starving, the crippled and the blinded, even as the military authorities boast of their inevitable victory.

It is said that no battle plan survives contact with the enemy. How then, are a bunch of untrained girls to deal with the realities of a battle? The adventure and the glory of the Empire and Emperor die under withering fire, as the girls and their teachers struggle from one awful situation to the next; the only respites are the brief regroupings, when they discover their classmates are not all dead. They witness duty, honor, compassion die over the months of the battle, and stagger forward, supporting each other.

It's a grim, shocking movie from a novel by Yôko Mizuki. It's been remade twice. I can't imagine it's been improved on.