The Lenten synod, convened by Pope Gregory VII, took place amid escalating tensions between the spiritual and temporal powers in medieval Europe. Henry IV, Holy Roman Emperor, found himself at odds with the papacy, primarily over the investiture controversy, where kings and emperors sought to appoint bishops and abbots, directly affecting their power. The letter demanding Henry's abdication was sent by his own bishops, encouraged by the Pope to diminish Henry's authority. In an unprecedented move, Pope Gregory VII excommunicated Henry amidst this synod, invalidating Henry's rule and declaring that he was no longer part of the Christian community. This action not only stripped Henry of his divine right to govern but also galvanized opposition against him within his own territories.

The synod and subsequent excommunication had immediate repercussions for the power dynamics in Europe. While Henry initially sought to undermine the Pope’s authority, the excommunication would rally different factions, creating a rift within the Holy Roman Empire. Gregory’s decision marked a pivotal moment in the broader narrative of the church versus state, illustrating the increasing power of the papacy in political matters. Henry IV’s excommunication set off a series of events that culminated in the famous Walk to Canossa, where he sought forgiveness from the Pope in 1077, showcasing the lengths to which rulers would go to regain favor.