The Device Forts, also known as Henrician castles and blockhouses, were a series of artillery fortifications built to defend the coast of England and Wales by Henry VIII. They ranged from large stone castles, to small blockhouses and earthwork bulwarks. Armed with artillery, the forts were intended to be used against enemy ships before they could land forces or attack vessels lying in harbour. The castles were commanded by captains appointed by the Crown, overseeing small garrisons of professional gunners and soldiers, who would be supplemented by local militia in an emergency. The Device programme was hugely expensive, costing a total of £376,000, much of it raised from the proceeds of the Dissolution of the Monasteries.