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
Giselbert, Count of Clermont daughter of Giselbert and obtained the title by marriage. The second is that the activities of the occupants of Clermont in 1095, Giselbert and Fredelon, who some regarded as brigandage, were perceived by these two as the legitimate levying of tolls on river traffic. A 1095 entry in the chronicle of Giles of Orval reveals that what Otbert's objective was accomplished by purchase. The acquisition of Clermont and its subsequent enfeoffment to his vassal Lambert was part of a consistent policy of purchase which also brought to the prince-bishop the important fortresses of Mirwart, Couvin and, Bouillon. This second theory