Urban II, pope (1088 to 1099), was born Odo (or Eudes) of knightly rank, at Lagery (near Châtillon-sur-Marne) and was educated for the church. He had already become archdeacon of Rheims when, under the influence of St. Bruno, his teacher, he resigned his preferement and entered the cloister at Cluny, where he rose to be prior. In 1078 Gregory VII summoned him to Italy, and made him cardinal-bishop of Ostia.
He was one of the most prominet and active supporters of the Gregorian reforms, especially as legate in Germany in 1084, and was among the few whom Gregory nominated as posible successors. Desiderius, abbot of Monte Cassino (who took the name Victor III) was chosen in the first instance to the difficult post, but after his short reign Odo was elected by acclamation (March 1088) at a small meeting of cardinals and other prelates held in Terracina. He frankly took up the policy of his great predecessor, but while pursuing it with equal determination showed greater flexibility and diplomatic finess. At the outset he had to reckon with the presence of the powerful antipope Clement III in Rome; but a series of well-attended synods held in Rome, Amalfi, Benevento, and Troia supported him in renewed declarations against simony, lay investiture, and clerical marriages, and a continued opposition to Henry IV.
In accordance with this last policy, the marriage of the countess Matilda of Tuscany with Guelph of Bavaria was promoted, Prince Conrad was helped in his rebllion against his father and crowned king of the Romans at Milan in 1093, and the empress (Adelaide or Praxedes) encouraged in her charges against her husband. In a protracted struggle also with Philip I of France, whom he had excommunicated, Urban II finally proved victorious. But the most prominent feature in his pontificate, a feature indeed which marks an epoch in the history of Latin Christianity, is his connexion with the first crusade, which united Christendom under the headship of the Pope into one vast warlike confederacy.
The crusading movement took shape at Piacenza, where in March 1095 Urban received an embassy from the Byzantine emperor Alexius I Comnenus, asking help against the Muslims, and where a great council met, attended by numerous Italian, Burgundian, and French bishops and by so vast a concourse of monks and laymen that the public meetings had to be held in the open air outside the city. The still more enthusiastic council of Clermont was held in November of the same year.
Urban II died on 29th July 1099, fourteen days after the fall of Jerusalem to the Crusaders, but before the tidings of that great event had reached Italy; his successor was Paschal II.