Available free from the Baen Free library, Sheepfarmer's Daughter, by Elizabeth Moon, a fantasy novel about a young woman, Paksenarrion, aka Paks, who runs away from home to join the army. It's a light story, but some of Paks' adventures become quite absorbing. Obviously, she is going on to bigger and better things in the series, possibly as a paladin. The gods seem to favour her.
The story is light but the prose is good enough to keep you reading, and some attempt has been made to show what a soldier's life might really be like even in such a fantasy setting.