Consider Phlebas

As a mercenary bound to the Idurans, a valiant war-faring race, Phlebas seemed to be a typical hero of our times. And the soft, slippery, Machiavellian Culture his employers are fiercely combating seems conventionally lacking in moral fiber.
Only gradually will he discover how mistaken he was. But this is far too late for him, and he dies uselessly, for nobody will ever remember his derisory crusade, just a skirmish in the titanic war between the Culture Minds and the immortal Idurans.
A war that spread across the galaxy, bringing doom to stars themselves.