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
Simon II of Clermont-Nesle king engaged the best available lawyers for his case. The conflict led in 1309 to the moving of the Papal court, under Pope Clement V (c. 1264–1314), to Avignon, outside the king's realm. Simon was a son of Simon II of Clermont, Seigneur of Ailly, Maulette and Nesle (c. 1216–1286) by Adele of Montfort (d. 1279), daughter of Amaury VI of Montfort. The father was a counsellor of King "Saint" Louis IX of France and was appointed regent ("lieutenant") while the king went away on the Seventh Crusade. Simon had three brothers and at least one sister, whose son was