Shields

Shields provide an impenetrable barrier to protect your cities and buildings against enemy attacks. They can be applied at any point to any lands that are under your control, and are also triggered on a land after it has been raided. Shields can last up to 24 hours depending on if you have bought a shield or even a few days, if you are upgrading a high level land - before they deactivate. Shields protect the land they are covering from being looting or captured. However, if you launch an attack while your lands are shielded, all your shields will be broken, and you'll immediately become vulnerable to attack.

If a land has been looted by another player, after a few attacks, a shield will automatically raise over the looted land for one hour. A shield does not raise after a single attack - you can be attacked multiple times, and then a shield will raise.
 * A captured Land will be shielded for 4 hours.
 * A raided castle gets shielded for 12 hours.
 * A raided Land gets a shield for 1 hour.
 * If the defender is attacked 8 times in 2 hours, then all Lands will be shielded for 6 hours.