Tides of Light — Gregory Benford

Set against the magnificent, furious backdrop of the Galactic Center, here is a drama as compelling as the towering Great Sky River. A small human band flees from a threat it cannot hope to match -- enormously superior artificial minds embodied in great insectlike machines. This last remnant of humanity is led by Killeen, a man elevated to command in desperate times by his luck and daring. He manages to reach a new planet where he encounters vast wonders -- a planet-coring cosmic string, an organic life-form the size of an entire world, another group of humans led by a strange messianic ruler -- and even greater dangers from the most awesome beings they have yet to face.

Their battle for survival reaches overwhelming dimensions. But they will gain an unexpected ally. And they will contribute shockingly to the new order of life that is developing around them.