He initially fought against the Roman Empire during the First Jewish–Roman War as general of the Jewish forces in Galilee, until surrendering in AD 67 to the Roman army led by military commander Vespasian after the six-week siege of Yodfat. Josephus claimed the Jewish messianic prophecies that initiated the First Jewish–Roman War made reference to Vespasian becoming Roman emperor. In response, Vespasian decided to keep him as a slave and presumably interpreter. After Vespasian became emperor in AD 69, he granted Josephus his freedom, at which time Josephus assumed the Emperor's family name of Flavius.
He initially fought against the Roman Empire during the First Jewish–Roman War as general of the Jewish forces in Galilee until surrendering in AD 67 to the Roman army led by military commander Vespasian after the six-week siege of Yodfat. Josephus claimed the Jewish messianic prophecies that initiated the First Jewish–Roman War made reference to Vespasian becoming Roman emperor. In response, Vespasian decided to keep him as a slave and presumably interpreter. After Vespasian became emperor in AD 69, he granted Josephus his freedom, at which time Josephus assumed the Emperor's family name of Flavius.