Recently started reading a history book on females throughout the ages that have joined the military pretending to be male and got an urge to read some manga. Read Kaze yo, Banri o Kake yo, Kaze Hikaru and some other i dont remember at the moment. Real and fictional, past and future evertting is go.

"The oldest and strongest emotion of mankind is fear, and the oldest and strongest kind of fear is fear of the unknown"

I have not read these, and they are all pretty short but they fit your description

Sekai no Hate no Sougen de -this one is just a oneshot
Shiroi Majo
and then there is also Kenkouki - Hi no Kuni Daiteikokugun Kurenai Ikki Tousentai that i found but not only is it on hiatus, but there are only 2 chapters out and it does not look very good so...

[img]http://24.media.tumblr.com/3b280fafb72cad0f718be64368e64ca7/tumblr_myylzmuiY41rw3pzao4_250.gif[/img]
Like educational manga? take a look at Ed U. Manga's list of manga here

I really advice you to read Chang Ge Xing : it fits your description (I think ?) and it is so interesting 🙂

More: Ao no Souyoku - Phantom of Dragon (nothing special), Gaikou Kakkaku (i may misremember and no translation is out), Gunka no Baltzar (1 of basically 2 female characters who somewhat matter), Joan (more takes exist of course) and Versailles no Bara (the classic example).
Edit: Frogot Basara, thx kagehoshi.

I also read EU/US comics and am a librarian.
Manga-Masters, My ANN-Lists + Imdb

Basara, (if you haven't read it already) not joining but building an army of her own pretending to be her brother, one of the most awesome female lead in my opinion

Read some of Basara and Chang Ge Xing, not exactly what i was looking for. Will take a closer look at the others. Please keep them coming!

"The oldest and strongest emotion of mankind is fear, and the oldest and strongest kind of fear is fear of the unknown"