Born Odo of Chรขtillon in France, he became a monk at the influential Abbey of Cluny and later served as a close advisor to Pope Gregory VII, strongly supporting the Gregorian Reforms aimed at purifying the Church.
He was elected Pope in 1088 during a tumultuous period of conflict with the Holy Roman Emperor, known as the Investiture Controversy, forcing him to spend his early papacy in exile from Rome.
In 1095, at the Council of Piacenza, he received a desperate plea for military assistance from the Byzantine Emperor Alexios I Komnenos, whose empire was under severe threat from the Seljuk Turks.
Later that year, at the Council of Clermont in France, Urban II delivered a highly impassioned and historical sermon. He urged Western Christians of all classes to march to the East, promising the remission of sins for those who fought to liberate the Holy Land.
His call to arms successfully launched the First Crusade, rallying thousands under the cry 'Deus vult' (God wills it). Tragically, he died on July 29, 1099, just weeks before the triumphant news of the Crusaders' capture of Jerusalem reached Europe.