The Dark Ascent — Walter H. Hunt

"The human-zor war is long over, and the now-allied former foes face the shape-changing vuhl, who enjoy their share of devastating victories. Still, the zor and humans were warned and don't entirely lack resources. But something is going on that isn't quite right. The power behind the vuhl, which was also behind the human-zor conflict, has motives that are only hinted at here. Suffice it to say that the history of the zor does not match its legend. Ex-commodore Jackie Laperriere...can choose among different courses this time, and the vuhl are finally thrown into confusion when roundly defeated. They react with a regime change, but the wars' mysterious backers continue playing strange games, occasionally seeming to help human forces, more often supporting the vuhl--always pursuing goals that may not coincide with those of ostensible allies. This surprisingly thoughtful space opera, lacking neither adventure nor battles, considers issues of genocide and enmity in surprising depth." --BOOKLIST