The simple castles raised after the Norman conquest had been developedthroughout 11th and 12th centuries whilst the introduction of Islamic andByzantine fortifi... » 

The simple castles raised after the Norman conquest had been developedthroughout 11th and 12th centuries whilst the introduction of Islamic andByzantine fortification techniques from the late 12th century led to furtherdevelopments in castle architecture. These fortifications were to be welltested throughout the course of the 13th century as England was riven by theconflict characterized by prolonged sieges between the monarchy and powerfulmagnates. As well as providing the focus for warfare castles increasinglybecame the centres of their communities providing a more permanent base forthe lord his family and retainers as well as acting as centres for justiceand administration. «