The Crusades were a series of religious expeditionary wars blessed by the Pope and the Catholic Church, with the stated goal of restoring Christian access to the holy places in and near Jerusalem. The Crusades were originally launched in response to a call from the leaders of the Byzantine Empire for help to fight the expansion into Anatolia of Muslim Seljuk Turks who had cut off access to Jerusalem. The crusaders comprised military units of Roman Catholics from all over western Europe, and were not under unified command. The main series of Crusades, primarily against Muslims, occurred between 1095 and 1291. Historians have given many of the earlier crusades numbers. After some early successes, the later crusades failed and the crusaders were defeated and forced to return home.