Recs for military fantasy

So I’m in the veryy early stages of writing my own book, and I am a big believer that to make something new, you gotta understand the old/the standard, so I hoping for some recs to help with my research.

My story for context features a heavily isolated military society (almost spartan) with a hard magic system certain bloodlines can access. Necromancy adjacent magic being the most impactful on the world and society (both good and bad ways).

Theme wise it is very critical of the military industrial complex, coming to realize one’s own prejudices, and bringing balance back to nature.

For context, books I have on my tbr list include the Poppy Wars, rereading Ember in the Ashes, And I Darken, and The Locked Tome (it’s been a Hot minute), but I would like some more adult books, especially if they are a shorter series. (NOT fourth wing)

Also any recs on historical books to use as references, such as spartan culture would be great. Thanks guys!