Aoki Hagane no Arpeggio (Arpeggio of Blue Steel) is a military manga that’s getting an anime adaptation to be directed by Seiji Kishi (P4A, Angel Beats!) and produced by SANZIGEN (Black Rock Shooter).
A synopsis from MyAnimeList:
In the story, a Fleet of Fog loaded with super weapons suddenly appear all over the world. Without the ability to withstand this fleet, humanity was defeated and could no longer travel the seas. 17 years after the devastating naval war, Chihaya Gunzou and his friends somehow commandeer a Fleet of Fog submarine and rename it I-401. Together with Iona, they take on the Fleet of Fog.
There have been several instances of anime/manga that featured girls in the military, but this is the first that I’ve seen that showcases the naval branch exclusively. As to why it’s always all girls, I’ll answer that by saying “it’s anime, and I’m not complaining” (though, I know a lot of people do).
While it may be too early to draw comparisons (and I’ve never read the manga), I feel like I’d enjoy the series because I liked Girls und Panzer and Sora no Woto a lot. Of course, those series get mixed reviews as it is and they’re all so different from each other, so things are kind of up in the air. Also, the amount of CGI is rather off-putting, but I did end up getting used to it in Girls und Panzer.
No release date has been set yet.
Check out the official website: http://www.aokihagane.com/