Urban II was a Benedictine monk who served as the head of the Catholic Church from 1088 until his death in 1099. Born Odo of Châtillon, he previously held positions as the prior of Cluny and the cardinal-bishop of Ostia. He is most famous for his speech at the Council of Clermont, which launched the First Crusade by calling for military expeditions to reclaim the Holy Land. During his papacy, he navigated intense political conflicts involving the Holy Roman Empire and worked to implement various Gregorian reforms within the church hierarchy.