Christianity in the 11th century when the Seljuk Turks closed Christian pilgrimages and assailed the Byzantines, defeating them at the Battle of Manzikert. Emperor Alexius I asked for aid from Pope Urban II for help against Islamic aggression. Urban II called upon the knights of Christendom in a speech made at the Council of Clermont on 27 November 1095, combining the idea of pilgrimage to the Holy Land with that of waging a holy war against infidels. The First Crusade captured Antioch in 1099 and then Jerusalem. A traditional numbering scheme for the crusades totals nine during the 11th to 13th centuries. Elements of the
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