When the Jews revolted against Rome in 66 CE, Josephus, a Jerusalem aristocrat, was made a general in his nation's army. Captured by the Romans, he saved his skin by finding favor with the emperor Vespasian. He then served as an adviser to the Roman legions, running a network of spies inside Jerusalem, in the belief that the Jews' only hope of survival lay in surrender to Rome. As a Jewish eyewitness who was given access to Vespasian's campaign notebooks,...