How did the promise of an indulgence encourage participation in the First Crusade?

At the Council of Clermont in 1095, Pope Urban II granted a plenary indulgence to those who participated in the First Crusade to aid Christians in the East.12

This promise served as a powerful incentive because it offered the full remission of all penance for sin. In the context of medieval Christianity, where believers sought to address the temporal punishment due for their sins, this act was viewed as a significant means of spiritual redemption and expiation. By framing the military expedition as a holy work pleasing to God, the Church transformed the act of fighting into a form of religious devotion.123456

For many participants, the Crusade provided a way to channel their religious fervor and seek salvation through service to the Church. This spiritual assurance, combined with the era's deep religious consciousness and apocalyptic expectations, encouraged a massive and immediate response from both knights and the general populace.136