Beaumaris as a concentric castle

Beaumaris is one of the clearest examples of a concentric castle, with defensive layers arranged in an unusually symmetrical plan on the open ground of Anglesey. Making room for the fortress probably involved clearing an existing settlement while a new or enlarged town developed beside it, though the balance of displacement and migration remains uncertain. The moat, barbican, gates, and sally ports were meant to interrupt a direct assault. Because the fortress was designed to endure a siege instead of supporting constant sorties, even one proposed gate was closed as a potential weakness. A dock and water-filled moat would also allow reinforcement and prolonged resistance from the sea.