The Uplift War, David Brin
This is the third in Brin's Uplift series. This story is set parallel to his second book. This book follows the invasion and capture of one of mankind's world. A guerrilla war is fought against the powerful alien invaders although in the end luck has a big part to play. It's one I really enjoy for it's battles against overwhelming odds, interesting characters, and a fair grasp of science (although some of it is made up science.) It almost makes me want to read the subsequent story... if only he had squeezed that into a single book rather than stretching it out into a trilogy.