The Chosen — S.M. Stirling; David Drake

Planted by interstellar probes on hundreds of human- /occupied worlds, the downloaded personalities of Raj Whitehall and the ancient battle computer known as Center work together for planetary unity. Their goal is to prepare those worlds for membership in the Second Federation of Man. But on one planet they do the opposite: on Visager they work to prevent unity. For on Visager a nation-state of vicious militarists is about to start the final war to unite their world -- once that is accomplished and their technology has matured they will turn outward, bringing their fatal racist infection to I the stars.

John Hosten is the son of a high general of the Chosen. Jeffrey Farr is the son of an admiral of the only nation on Visager that might be capable of halting the onslaught. Through a strange twist of fate they have become as brothers united in their hatred of all that the Chosen hope to do. Only they -- with the aid of the disembodied voices of their mentors from the stars -- stand between eternal tyranny for their world and eternal war for the galaxy.