Extinction, the Second Book in the Star Force Series, by B.V. Larson.
An Entertaining read, with great strategy interspersed throughout, as the second book in the series, you find Larson, getting better at not rushing through some of his action, and finding better ways to flesh it out. In his first book of the series, the beginning was a little rushed but it was still a worthwhile read if you are into dramatic sci-fi alien conquest type of stories. If you want to explore the Star Force universe follow this link for an introduction to the writing styles of B.V. Larson.
Book 1 Star Force Series