The game does not actually inform you this, however Naval Battles are open from the very starting and you can play them whenever you like. Naval Battles are mini games where you require to the seas to prevent the marine intrusions from the surrounding kingdoms. Wait on the cross-hair to line up right in the center of the intending line, then let your cannons loose! It takes a little practice to get used to the timing, however the closer you are the bulleye, the more damage you do. Each enemy ship you effectively remove will earn you a great amount of experience for all of your council members.