How does the Shield work?
You can deploy a Shield to protect your Base from hostile Armies for a limited amount of time: 4-hours, 8-hours or 24-hours. When your Shield is active any hostile Army will be unable to harm your Base or plunder your resources. To deploy a Shield either tap your Base on the Map or go to your Inventory and use a Shield from there. If you are out of Shields you can find more in the Black Market a.k.a in-game Shop. Once your Shield is active you can still send out an Army to reinforce friendly targets or mine. But be aware that performing hostile activities will disable your Shield.