partially reversed for provinces that were judged to be especially vulnerable or in internal disorder. Capitalizing upon this precedent and taking it one step further, the emperor Maurice sometime between 585 and 590 created the office of exarch, which combined the supreme civil authority of a praetorian prefect and the military authority of a magister militum, and enjoyed considerable autonomy from Constantinople. Two exarchates were established, one in Italy, with its seat at Ravenna (hence known as the Exarchate of Ravenna), and one in Africa, based in Carthage and including all imperial possessions in the western Mediterranean. The first African exarch was the patricius Gennadius. Among the provincial changes, Tripolitania was detached from the province of Africa and placed under the province of Egypt, Mauretania Caesariensis and Mauretania Sitifensis were merged to form the new province of "Mauretania Prima", while Mauretania Tingitana, effectively reduced to the city of Septum (Ceuta), was combined with the citadels of the Spanish coast (Spania) and the Balearic Islands to form "Mauretania Secunda". The Visigothic Kingdom was a continuous threat to the exarchate. The African exarch was in possession of Mauretania II, which was little more than a tiny outpost in southern Spain. The conflict continued until the final conquest of the last Spanish strongholds in c. 624 by the Visigoths. The Byzantines retained only the fort of Septum (modern Ceuta), across the Strait of Gibraltar. During the successful revolt of the exarch of Carthage, Heraclius the Elder, and his namesake son Heraclius in 608, the Berbers comprised a large portion of the fleet that transported Heraclius to Constantinople. Due to religious and political ambitions, the Exarch Gregory the Patrician (who was related by blood to the imperial family, through the emperor's cousin Nicetas) declared himself independent of Constantinople in 647. At this time the influence and power of the exarchate was exemplified in the forces gathered by Gregory in the battle of Sufetula also in that year where more than 100,000 men of Amazigh origin fought for Gregory. The Arab Muslim conquest In 647, the first Islamic expeditions began with an initiative from Egypt under the emir Amr ibn al-As and his nephew Uqba ibn Nafi. Sensing Roman weakness they conquered Barca, in Cyrenaica, then moved on to Tripolitania, where they encountered resistance. Due to the unrest caused by theological disputes concerning Monothelitism and Monoenergism, the exarchate under Gregory the Patrician distanced itself from