Saint Urban II was a pope who served from 1088 to 1099. He is best known for initiating the First Crusade in 1095, which aimed to reclaim the Holy Land from Muslim control. His call to arms at the Council of Clermont inspired many knights and common people to join the crusade, leading to significant military campaigns. Urban II emphasized the spiritual benefits of participating in the crusade, promising forgiveness of sins and eternal salvation for those who fought. His leadership helped shape the course of medieval Europe and the relationship between Christianity and Islam.