Sassinak

Sassinak was twelve when the raiders came. Old enough to be used, young enough to be broken - or so they thought. But they reckoned without the girl’s will, forged into a steely resolve to avenge herself on the pirates who had killed her parents and friends.
When the chance comes to escape, Sassinak grabs it, thanks to the help of a captured Fleet crewman. Returned to the Federation of Sentient Planets, she initiates her revenge by joining Fleet as a raw recruit, surprising everyone by her rapid rise to senior rank. And then her vengeance begins in earnest.
Anne McCaffrey and Elizabeth Moon have woven a story worthy of Robert A. Heinlein in its tough- mindedness, reminiscent of Larry Niven and David Brin ‘ in its description of human and alien races coming together both as friends and enemies.