Exodus: Empires at War: Book 12: Time Strike.

The New Terran Empire is still trying to recover from the Ca'cadasan strike that left over three hundred million dead and ripped the heart out of the ship production of Central Docks.The Donut, the huge station in orbit around the Supersystem black hole, was almost destroyed in that strike, and its defenses have been strengthened considerably.

That Caca strike didn't do all they had wanted, but it had hurt the Empire's war making capabilities. The Ca'cadasans are at it again, with a two-pron...