Following the death of Pope Victor III on 16 September 1087, Odo of Lagery was elected pope as Urban II on 12 March 1088. His election took place not in Rome but in Terracina, south of the city, since Rome itself was controlled by the antipope Clement III, who had been installed with the backing of the Holy Roman Emperor Henry IV during the Investiture Controversy. This long-running conflict centred on whether secular rulers or the papacy held the authority to appoint bishops and other senior church officials.

Urban II was a committed supporter of Pope Gregory VII and the Gregorian Reform, ⓘ a movement that sought to restore clerical discipline, enforce clerical celibacy, and assert the Church’s independence from secular power. His election therefore represented continuity with Gregory VII’s reforming programme and a direct challenge to imperial control over the Church. For several years Urban lacked effective control of Rome itself, ruling instead through synods, legates, and diplomatic alliances, gradually winning support among reform-minded clergy and lay rulers across Western Europe.

Urban II’s pontificate reached its most enduring historical significance at the Council of Clermont on 27 November 1095. There, responding to an appeal from the Byzantine emperor Alexius I Comnenus for assistance against the Seljuk Turks, Urban called upon Western knights to provide military aid to the Eastern Church. His speech, preserved in several later accounts, promised spiritual rewards for those who took part and framed the expedition as an act of penitential warfare. This appeal directly initiated what later became known as the First Crusade.

While the crusading movement would take on forms and consequences far beyond Urban’s original intentions, his role in its proclamation placed the papacy at the centre of a vast international religious and military enterprise. At the same time, he continued to pursue reform within the Latin Church, appointing loyal bishops, strengthening papal legates, and undermining the position of the antipope Clement III.

Urban II died in Rome in 1099, shortly after the capture of Jerusalem by crusading forces, though he did not live to receive news of the city’s fall. He was beatified in 1881 by Pope Leo XIII, and his feast day is celebrated on 29 July.