Britain was in a state of civil war for much of the Middle Ages, as nobles feuded with each other or revolted against the king. Lords and kings built castles for protection and to control lands. Other castles were built by invaders to stamp their authority, such as the motte and bailey castles built after the Norman Conquest.
At other times castles were built to defend against foreign invaders, like Henry VIII’s coastal forts, or later as homes. Castles were also built when England, Scotland and Wales fought wars with each other. As a result of this long and warlike history, over 1,500 castles were built in England alone.