Vicarius in the context of "Battle of Mu'tah"

In the Late Roman Empire, usually dated AD 284 to 641, the regional governance district known as the Roman or civil diocese was made up of a grouping of provinces each headed by a vicarius, the vicars being the representatives of praetorian prefects (who governed directly the dioceses they were resident in). There were initially twelve dioceses, rising to fourteen by the end of the 4th century.

The term diocese comes from the Latin dioecēsis, which derives from the Ancient Greek dioíkēsis (διοίκησις) meaning 'administration', 'management', 'assize district', or 'group of provinces'.

Hispania was the Roman name for the Iberian Peninsula. Under the Roman Republic, it was divided into two provinces: Hispania Citerior and Hispania Ulterior. During the Roman Empire, under the Principate, Hispania Ulterior was subdivided into Baetica and Lusitania, while Hispania Citerior was reorganized as Hispania Tarraconensis.

Beginning with Diocletian’s Tetrarchy (AD 293), the territory of Tarraconensis was further divided to create the provinces of Carthaginensis and Gallaecia (also called Callaecia, the origin of the name of modern Galicia). All the Hispanic provinces on the mainland, together with the Balearic Islands and the North African province of Mauretania Tingitana, were later organized into the Diocesis Hispaniarum, governed by a vicarius.

A steward is an official who is appointed by the legal ruling monarch to represent them in a country and who may have a mandate to govern it in their name; in the latter case, it is synonymous with the position of regent, vicegerent, viceroy, king's lieutenant (for Romance languages), governor, or deputy (the Roman rector, praefectus, or vicarius).

The Diocese of Egypt (Latin: Dioecesis Aegypti; Greek: Διοίκησις Αἰγύπτου) was a diocese of the later Roman Empire (from 395 the Eastern Roman Empire), incorporating the provinces of Egypt and Cyrenaica. Its capital was at Alexandria, and its governor had the unique title of praefectus augustalis ("Augustal Prefect", of the rank vir spectabilis; previously the governor of the imperial 'crown domain' province Egypt) instead of the ordinary vicarius. The diocese was initially part of the Diocese of the East, but in ca. 380, it became a separate entity, which lasted until its territories were overrun by the Muslim conquest of Egypt in the 640s.

Lucius Domitius Alexander (died c. 310), probably born in Phrygia, was vicarius of Africa when Emperor Maxentius ordered him to send his son as hostage to Rome. Alexander refused and proclaimed himself emperor in 308.

The most detailed if somewhat confusing description of the insurrection is given by Zosimus (II, 12 and 14). He reports that Maxentius sent his portrait to Africa to gain recognition as Emperor there. The troops resisted because of their loyalty to Galerius. Maxentius ordered Domitius Alexander, the vicar of Africa, to send his son to Rome to secure his loyalty. Alexander refused and was crowned Emperor by his army. The incident was probably caused by the conflict between Maxentius and his father Maximian in April 308, and Zosimos confused Galerius with Maximian in his account.

The Diocese of Hispania was a late antique administrative unit (Dioecesis) of the Roman Empire on the Iberian Peninsula. It existed from 298 to about 461 AD. Its capital was Augusta Emerita. The diocese was governed by a vicarius responsible to the praetorian prefect of Gaul.