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 VI Pope Urban VI Pope Urban VI (; c. 1318 – 15 October 1389), born Bartolomeo Prignano (), was Pope from 8 April 1378 to his death in 1389. He is so far the last pope to be elected from outside the College of Cardinals. His reign, which began shortly after the end of the Avignon Papacy, was marked by immense conflict between rival factions as part of the Western Schism. Born in Itri, Prignano was a devout monk and learned casuist, trained at Avignon. On 21 March 1364 he was consecrated Archbishop of Acerenza in the Kingdom of Naples. He