The Fifth Empire of Man — Rob J. Hayes

The Pirate Isles are united under Drake Morrass' flag, but the war has only just begun. There's still a long way to go before he's able to call himself King. The Five Kingdoms and Sarth have assembled a fleet of ships unlike any the world has ever seen, and they intend to purge the Pirate Isles once and for all. Meanwhile, Elaina Black is securing herself powerful allies and the forces those allies can spare. She's set her course for the throne -- either by Drake's side or over his dead body.