Invasion

Captain Loren Stone is in command of the fighter wing of the Confederation ship Avenger, and it's been a great run. He gets to see the galaxy, fly a state of the art fighter, and his friends joke that he must fantasize about being himself.
The time has come, however, to make a choice. His next rotation will put him behind a desk, and he and his wife have been waiting to start a family, so it's time to get out and start the next chapter of their lives.
Those well-laid plans are put on hold by a shocking attack carried out on the Confederation by a mysterious and powerful alien foe advancing through the galaxy.
The alien invaders burst onto the scene, sweeping away those like the Confederation that fight back, and convincing others to not even try to fight, for they claim the galaxy was once theirs and they are simply returning to their rightful place.
After Loren sees this, he faces a choice that's easy to make but hard to live with: he will stay and fight, and either help drive the invaders from his corner of the galaxy, or die trying.