In 533 AD, the Byzantine general Belisarius reconquered the former Diocese of Africa from the Vandals on behalf of the Emperor Justinian I. All the territory west of Caesarea had already been lost by the Vandals to the Berber "Mauri", but a re-established "Dux Mauretaniae" kept a military unit at Septem (modern Ceuta). This was the last Byzantine outpost in Mauretania Tingitana; the rest of what had been the Roman province was united with the Byzantine part of Andalusia under the name of the Praetorian prefecture of Africa, with Septem as administrative capital.