In 602, the final war between the Byzantine Empire and its eastern rival the Sasanid Empire (Persian Empire) broke out. In 613 the Persians invaded the Levant and the Jews revolted against the Byzantines, hoping to secure autonomy for Jerusalem. The following year Persian-Jewish forces captured Caesarea and Jerusalem, destroying its churches, massacring its Christian population, and taking the True Cross and other relics as trophies to the Persian capital Ctesiphon. The event sent shock-waves through the Christian world. Since the days of Constantine the Great, Jerusalem had been the emblematic capital of Christianity and the symbolic center of the world. The Jews gained dominance over Jerusalem, but the Persians found it more expedient to side with the Christians who constituted the overwhelming majority of the population and in 617 the Persians returned the city to them. Meanwhile, the Roman emperor Heraclius began a successful counter-offensive. By 627/8 he was advancing into the Persian heartland. The Persians sued for peace and had to return the Roman provinces they had captured and the stolen relics. In March 629, Heraclius triumphantly returned the True Cross to Jerusalem. Heraclius had promised the Jews pardon for their revolt. However, at the prompting of the Christian leadership, Heraclius went back on his promise. The Jews were expelled from Jerusalem and thousands were massacred.