Citadel

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.