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 Pius II was not an eminent scholar. His Latin was fluent, but he knew little Greek. Still, his writings have many good qualities. Pope Pius II inaugurated an unusual urban project, perhaps the first city planning exercise in modern Europe. He refurbished his home town of Corsignano (province of Siena, Tuscany) and renamed it Pienza, after himself. A cathedral and palaces were built in the best style of the day to decorate the city. They survive to this day. Pope Pius II Pope Pius II (, ), born Enea Silvio Bartolomeo Piccolomini (; 18 October 1405 – 14 August 1464) was Pope