The Ten Thousand by Paul Kearney
The world of Kuf is a brash jewel swarming with all manners of races and peoples. The Assurian Empire is dominant, prestigious and thought to be invincible. However, this ancient colossus is about to be shaken to its very foundations. Ten thousand elite mercenaries of a legendary race known as the Macht are hired by an Empire exile to take the throne by force. But when their employer is killed, and they are surrounded by Empire armies, the Ten Thousand find themselves abandoned. This is the story of their fight for freedom.