Citadel

An interesting idea of how humanity might fit in with alien civilizations. In my opinion, the enjoyment of the book was hindered by a couple of the author's techniques. Some parts of the book seem to be written for video, with each paragraph, the scene may shift from a group of people on earth or to a different group of people in space. This is difficult for the reader to follow by the author's words alone. The author also has a tendency to refer to characters in a confusing number of ways. A single character may at times be referred to by their name, at other times by their military rank or an abbreviation, or a nickname, or a slang term, or a general description ... in some areas of the book, it's hard to guess how many people are in the room because their names keep changing.

Citadel is the second novel in John Ringo's Troy Rising series. Humanity still faces relentless foes that intend to exterminate the human race. Under the leadership of Tyler Vernon the race must rise to the challenge. It is still a case of live free or die. This is good space opera.
Don't skip the afterward. In his writing, Ringo goes against current literary trends somewhat by creating characters that are competent, honorable, and courageous. Many of those are women. In an afterward to the book, Ringo explains exactly why he frequently creates strong women characters and he introduces the real-life models that have inspired those characters.