You have strengthened the walls surrounding the castle, but that is not enough, the guard on the tower is necessary to contain and repel attacks by enemy army. The enemy was not asleep, and scored in the numbers of new mercenaries - orcs and ogres giants. They do not bring down an ordinary stone, using poisoned arrows, stars, steel, fire projectiles. Upgrade your weapon to a bow flew not one, but a pack of arrows and destroy whole ranks of the monsters.