A Talent for War — Jack McDevitt

Everryone knew the legend of Christopher Sim. Fighter. Leader. An interstellar hero with a rare talent for war, Sim changed mankind's history forever when he forged a ragtag group of misfits into the weapon that broke the back of the alien Ashiyyur.

But now, Alex Benedict has found a startling bit of information, long buried in an ancient computer file. If it is true, then Christopher Sim was a fraud.

For his own sake, for the sake of history, Alex Benedict must follow the dark track of a legend, into the very heart of the alien galaxy--where he will confront a truth far stranger than any fiction imaginable...