Although he intended to cooperate with Henry IV at the outset of his papacy, Gregory VII was drawn into a terrible conflict with the king because of Henry’s refusal to obey papal commands. Emboldened by his success in 1075 against the Saxons, Henry took a firm stand against Gregory in disputes over the appointment of the archbishop of Milan and a number of Henry’s advisers who had been excommunicated by the pope. At the synod of Worms in January 1076, Henry took the dramatic step of demanding that Gregory abdicate, and the German bishops renounced their allegiance to the pope. At his Lenten synod the following month, Gregory absolved all men from their oaths to Henry and solemnly excommunicated and deposed the king. The situation quickly became desperate for Henry, who both lost much support and faced a reinvigorated revolt. In October Gregory’s legates and leaders of the German opposition assembled at Tribur (modern Trebur, Germany) to decide the future of the king, who by this point had been abandoned by his last adherents. Gregory was then invited to attend a meeting at Augsburg the following February to mediate the situation. Henry hastened to meet Gregory at Canossa before the pope reached Augsburg, however, and appealed to him as a penitent sinner. Gregory had little choice but to forgive his rival and lifted the excommunication in January 1077. Despite Gregory’s reconciliation with Henry, the princes elected Rudolf of Rheinfelden king at a gathering in Forchheim in March.

The civil war that now broke out lasted almost 20 years. A majority of the bishops, most of Rhenish Franconia (the Salian homeland), and some important Bavarian and Swabian vassals sided with Henry. He thus held a geographically central position that separated his southern German from his Saxon enemies, who could not unite long enough to destroy him. With the death in battle of Rudolf of Rheinfelden in 1080 and the demise of another antiking, Hermann of Salm, in 1088, the war in Germany degenerated into a number of local conflicts over the possession of bishoprics and abbeys. Henry was also successful in the larger struggle with Gregory, invading Italy and forcing the pope from Rome in 1084. At that time, Henry elevated Wibert of Ravenna to the papal throne as the antipope Clement III, who then crowned Henry emperor.

The situation remained in flux throughout the rest of Henry’s reign. In 1093 Henry was nearly toppled by a revolt led by his son Conrad, and a revived papacy under Urban II challenged the legitimacy of Clement. In 1098 the tide turned again when Henry appointed his other son, Henry, as his heir and relations with the bishops and papacy improved. Ultimately, however, Henry’s reign was doomed to failure by one final revolt. Even his apparent triumph at Canossa was tempered by his loss of status as a divinely appointed ruler.

Throughout these years the crown, the churches, and the lay lords had to enfeoff more and more ministeriales in order to raise mounted warriors for their forces. Though this recruitment and frequent devastations strained the fortunes of many nobles, they recouped their losses by extorting fiefs from neighboring bishoprics and abbeys. The divided German church thus bore the brunt of the costs of civil war, and it needed peace almost at any price.