1337: Edward the Black Prince
Edward III grants Berkhamsted Castle to his eldest son, Edward the Black Prince. The king also creates a new title for the prince: Duke of Cornwall. The title supersedes the earlier Earl of Cornwall title and is reserved for the heir apparent to the throne of England. The Black Prince who makes Berkhamsted Castle his main residence and expands the hunting grounds, establishing Berkhamsted Castle as the centre of the Duchy of Cornwall.