Final answer:
Pope Urban II launched the First Crusade in 1095 to regain control of the Holy Land and unify the church under his papacy, leveraging the religious sentiments of European Christians and extending papal influence.
Step-by-step explanation:
Pope Urban II is important in Catholic history because he initiated the First Crusade against Muslims in the Holy Lands. The call for the First Crusade was an effort to liberate the Christian Holy Land from non-Christian rulers, specifically from "Turkic" control, in 1095. This decision was influenced by Urban's investment in church reform and the defense of Christians living in the region, but it was also driven by political motivations such as asserting papal authority over the German emperors and testing the pope's influence over the Christian populace.
Urban II hoped the crusade would unify the church and reinforce the papacy's position. Despite the Byzantine emperor's request for mercenaries to aid against the Seljuks, Urban transformed this plea into a larger religious cause for European Christians who felt a profound connection to Jerusalem. His effective rhetoric and the concept of an "armed pilgrimage" mobilized large numbers of Christians, leading to multiple crusades over the following centuries against various perceived enemies of the church.