The main purpose of the Crusades, which were a series of religious wars from the 11th to the 13th centuries, was to reclaim the Holy Land, particularly Jerusalem, from Muslim control. Initiated by Pope Urban II in 1095, the Crusades aimed to assist the Byzantine Empire against Muslim expansion and to secure access for Christian pilgrims to sacred sites. The conflicts also propelled economic and political changes in Europe, leading to increased trade and the rise of a merchant class. While the Crusades had significant impacts on Christian-Muslim relations, they ultimately did not achieve their primary goal of permanently regaining the Holy Land for Christendom.