Diocese

   Diocletian (q.v.) reorganized the empire's provinces (q.v.) into 12 secular dioceses, each governed by a vicar. The dioceses were subsequently grouped into four larger prefectures (q.v.). The system lasted until the seventh century. Church organization followed suit, each ecclesiastical diocese having the same territory as its secular counterpart. In the same manner, church dioceses were subdivided into episcopal provinces. Each bishop of a diocese had the title of exarch (not to be confused with a secular exarch [q.v.]), later that of patriarch (q.v.). The only exception to this was the bishop of Constantinople (qq.v.), who was a patriarch without a diocese.