In Battle Castle, host Dan Snow explores the military engineering behind such strongholds as: Dover Castle, Krak des Chevaliers in Syria and Gibralfaro in Spain and details the legendary battles that testified to their impregnability. During the Middle Ages these fortified structures were the ultimate authority in any region they were built. Both defensive and offensive, they were centres of administration, symbols of power as well as concentrations of military might. But what was it that made each successful? Through dynamic location footage and immersive visual effects, this six episode series reveals the bloody history behind these fortifications and the weapons designed to defeat them. Each episode will climax with the ultimate test of each castle's strength: examining the epic battle that changed the course of history.