Koutetsu no Shoujotachi(2001)

Koutetsu no Shoujotachi

In a desperate attempt to hold off the powerful Federation, the Kingdom fields the Wölfin tank, but because their hopes depend on what was supposed to be a prototype, all their tanks must be manned by young girls with no experience of war. The story follows one girl and her unit as they train and fight.

(Source: MyAnimeList)