Pope military aid from Pope Urban II in the ongoing Byzantine–Seljuq wars. Urban, at the council of Clermont, called the First Crusade to assist the Byzantine Empire to regain the old Christian territories, especially Jerusalem. With the East–West Schism, the Eastern Orthodox Church and the Catholic Church split definitively in 1054. This fracture was caused more by political events than by slight divergences of creed. Popes had galled the Byzantine emperors by siding with the king of the Franks, crowning a rival Roman emperor, appropriating the Exarchate of Ravenna, and driving into Greek Italy. In the Middle Ages, popes struggled with
Pope Urban II her husband, Henry IV. He supported the theological and ecclesiastical work of Anselm, negotiating a solution to the cleric's impasse with King William II of England and finally receiving England's support against the Imperial pope in Rome. Urban maintained vigorous support for his predecessors' reforms, however, and did not shy from supporting Anselm when the new archbishop of Canterbury fled England. Likewise, despite the importance of French support for his cause, he upheld his legate Hugh of Die's excommunication of King Philip over his doubly bigamous marriage with Bertrade de Montfort, wife of the Count of Anjou. (The ban was