Pope Urban II
The major ecclesiastical impetuses behind the First Crusade were the Council of Piacenza and subsequent Council of Clermont, both held in 1095 by Pope Urban II, and resulted in the mobilization of Western Europe to go to the Holy Land. Byzantine emperor Alexios I Komnenos, worried about the advances of the Seljuks in the aftermath of the Battle of Manzikert of 1071 who had reached as far west as Nicaea, sent envoys to the Council of Piacenza in March 1095 to ask Pope Urban II for aid against the invading Turks.