Conventions of War — Walter Jon Williams

The universe has fallen into bloody chaos now that the dread empire of the tyrannical Shaa is no more -- at the mercy of the merciless insectoid Naxid, who now hunger for domination. But the far-flung human descendants of Terra have finally tasted liberty, and their warrior heroes will not submit. Separated by light-years, Lord Gareth Martinez and the mysterious guerrilla fighter Caroline Sula each pursue a different road to victory in tomorrow's ultimate battle -- for the new order will be far more terrible than the old ... unless one last, desperate stratagem can hold a shattered galaxy together.