Battles at Sea occur when two fleets get close in proximity and one attacks the other. Select the sword icon (Battle Commands) from the Sea Commands, and start the battle. (You cannot start a battle at night. Pay attention to the color of the sea to know whether it is day or night.)
You will win if you meet one of the following conditions:
● Sink the enemy’s flagship by reducing its durability to 0
● Eliminate the crew on the enemy’s flagship
● Defeat the enemy commodore in a duel
● Force the enemy’s flagship to flee