There are three strategies that can be used in battles; raid, attack, and defense. Raid is stronger than attack, attack is stronger than defense, and defense is stronger than raid. You can usually determine what kind of strategy an enemy is using, Always counterattack with the correct strategy. You can check their choice near the top of the screen, behind part of the user interface. A triangle shape indicates a raid, a square is an attack, and a rounded circle is defense. If a part of your fleet is destroyed, your next fleet can select a different strategy while your enemy will always be forced to stay with their current strategy.