What event did Urban II call for between 1096 and 1099?

Urban II called for the seizure of Jerusalem from Islamic rule during a series of events known as the First Crusade, which took place between 1096 and 1099. This call to action aimed to reclaim the Holy Land, particularly Jerusalem, for Christianity after it had come under Muslim control. The Pope's rallying cry at the Council of Clermont in 1095 appealed to the chivalric culture of Europe, framing the Crusade as a holy war and encouraging knights and common people alike to embark on this religious mission.

The religious and political motivations behind Urban II's call were significant in shaping the expansion of Christendom. He promised spiritual rewards and indulgences to those who participated, which was a powerful incentive for many Christians at the time. The First Crusade ultimately resulted in the capture of Jerusalem in 1099, creating a significant and lasting impact on Christian-Muslim relations and the geopolitical landscape of the region.