The Thirteenth Man

The Thirteenth Man takes place about 300 years before A Choice of Treasons in the interstellar kingdom known as the Realm, and before the formation of the Lunan Empire. King Lucius is a monarch with visions of empire, but he's also a fool who's bankrupted the royal treasury with failed little wars in his attempts at conquest. With a weak king on the throne, the Realm is now ruled more by the nine dukes on the Ducal Council.

Charlie Cass is the unacknowledged, bastard son of Cesare, Duke de Maris, one of the most powerful of the nine Dukes. Returning after five years in a squalid POW camp, Charlie finds that little has changed. The nine Dukes are conspiring against Lucius and each other. Lucius wants to annex one of the Independent States, another ill-advised attempt at conquest and a nice prelude to his next war. But to finance his aggressions he's now plotting with the Syndonese, Charlie's old enemies. When the Syndonese double-cross them all and take control of the Realm, leaving Lucius on the throne as a puppet, a free-for-all interstellar war erupts between the Realm, the Independent States and the Republic of Syndon. To save himself Charlie is forced to assume the mantle of the thirteenth Duke de Lunis, who, according to legend, is destined for the headsman's ax. But if he can survive the headsman, that same legend states that all may fall before the Thirteenth Man.