To protect yourself against sieges, you must have a strong army defending your town. If your army's overall power exceeds the attacker's power, he won't be able to start a siege. If you think that an enemy is going to besiege one of your towns, you may also try to attack him during his journey to you, in order to weaken his forces. To protect yourself from an enemy who is already besieging one of your towns, you can try and break the siege or ask someone to do so before the town is captured. To break a siege, select a hero with an army and click on your besieged town on the world map, followed by the "Siege" button. The siege window will pop up, allowing you to click the "Break siege" button to open the battle calculator and prepare for the fight. It is highly recommended that you scout the besieger's troops first. As soon as you are ready to break the siege, click the "OK" button on the battle calculator and your hero will leave to break the siege.