Cassan

The Duchies of Gwynedd are the largest feudal estates within the fictional Kingdom of Gwynedd in the Deryni novels of Katherine Kurtz. Each duchy is governed by a hereditary noble (a duke or duchess) who rules their land in exchange for swearing fealty to the Crown. Dukes are the most powerful nobles in the kingdom, wielding the power of high and low justice, and their authority in secular matters is surpassed only by the Crown. While dukes and duchesses enjoy the prestige and income of being in the ruling class of Gwyneddan society, they are required to pay appropriate taxes for their lands, see to the defense of their borders, and uphold the laws of the kingdom.