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
Geoffrey of Vendôme monastery to Popes Urban and Paschal. He took part in the councils held at Clermont in 1095, by Pope Urban; at Saintes, in 1096, by the Apostolic Legate Amatus of Bordeaux; and at Reims, in 1131, by Innocent II (1130–43). He also strenuously defended the ecclesiastical principles in the question of investitures, which he qualified in several small tracts as heresy and simony; he wrote in the same spirit to Pope Paschal II when the latter made concessions (1111) to Emperor Henry V (1106–25). Finally, he always defended firmly the prerogatives, the rights, and the property of his abbey at