His Conquering Sword

When conquerors clash - On the planet Rhui, the jaran tribes, under the leadership of Ilya Bakhtiian have ranged far in their campaign to subjugate all who will not willingly yield to their rule. Yet even as they prepare to besiege the royal city of Karkand, many another battle is being waged on a far more personal - and perhaps a more important - scale. For Ilya is married to Tess Soerensen, a woman born not on Rhui but on Earth, and woman, too, who is the only heir to Charles Soerensen, leader of the failed rebellion against the alien Chapalii Empire and now a duke of that same empire. And Charles has come to Rhui for two reasons: to reclaim his sister, and to decipher long hidden and invaluable data about the Mushai, the legendary Chapalii who once led his own rebellion against the Empire. But Tess has no desire to become anyone's puppet, and unless the three can make their own private peace and agree upon a common strategy for conquest, what hope do they have to overthrowing an Empire that was thriving before humans learned to walk erect? (from the back cover of the DAW Books first edition)