Warlord's World

From the back cover of the DAW first edition: "Vaughn Roberts of the almighty Interstellar Patrol was literally riding a roller coaster when he got the appeal for help from a damsel in distress. And being a gallant space hero with time on his hands he fell for it. She was a princess of Festhold, a planet addicted to soldiery, military adventure, and hairy-chested heroics - where unfortunately for the maiden her side was being outfoxed and outsoldiered by a combination of treachery and armed might. And when Roberts found himself the odd-man-out in that perpetual war game, he realized that he was still on a roller coaster, only this time with his life and the Interstellar Patrol as the unwilling patsies."