At the dawn of the High Middle Ages a papacy (pope) that was dedicated to reform emerged. At the time, only large landowners appointed their own priests, while dukes and kings selected bishops and abbots. The Catholic Church played an important role in the 10th and 11th century, but all important appointments to church positions were made by the lay(not priests or ministers) ruling class. Lay lords often sold church offices to unscrupulous people who recouped their purchase price by exploiting their people. The new reformers wanted a Christian commonwealth in which laymen no longer made church appointments. This revolutionary idea was supported by many nobles, however many of the churchmen opposed it.
Probably the most controversial person of this age was an Italian named Hildebrand. Hildebrand and another papal official named Humbert of Silva Candid emerged as leaders of the reform group. Both had served under Pope Leo IX, and both had left monastic life to become amazing leaders. Hildebrand was thought to be able to read minds, and most likely believed that he could do so. Together, in 1059, they issued a declaration called the “Papal Election Decree.” The decree stated that from now on the pope would be chosen by the churches cardinals. It didn't take long before the decree was challenged by both the Roman aristocracy and the Empire.
In 1073, Hildebrand became pope and changed his name to Gregory VII. Then, in 1075, a battle over control over church appointments erupted when Pope Gregory VII issued a decree banning “lay investiture.” King Henry IV responded at once, he said that it was his divine authority, and he should be allowed to rule the German church without interference from the Roman Catholic Church. The letter was addressed to, “Hildebrand, not pope but false monk.” Pope Gregory responded by stating that kings and emperors were, “gangsters who were headed to hell, and they had no right question his status or decrees.” Next, Gregory did something that shocked everyone, he excommunicated and deposed King Henry IV. King Henry's people refused to follow him because he had been excommunicated. They even threatened to elect a king to replace him.
Desperate, Henry IV crossed the Alps into Italy to seek Pope Gregory's forgiveness. Then, in January of 1077, at the castle of Canossa, in northern Italy, the two of them met in what became medieval history's most dramatic encounter. Henry, standing barefoot in the snow, promised to change his ways. Pope Gregory lifted the excommunication, and Henry returned to Germany in an attempt to rebuild his authority. However, he almost immediately reneged on his promises.
Lay Investiture would eventually end under the reign of King Henry V, in 1122. Under the “Concordant of Worms,” Henry agreed to give up lay investiture. From now on bishops and abbots were to be elected according to canon (church) law. The church had finally won, but monarchs still had a considerable amount of power over the church.