Confessor, archbishop of Vienne, born near Lyons, France; died Vienne, c475 He was distinguished for both secular and theological learning and was involved, 463, in a dispute with Pope Hilarius regarding the privileges of the See of ArIes. He is best known as the founder of the Rogation Processions. During his episcopate the relics of Saint Ferreolus were discovered and interred in the church which Mamertus built in honor of the saint. His remains were burned at Orleans by the Huguenots. Feast, May 11,.