The stories of Clovis at Tours, and of Charlemagne at Rome, show the vast importance of the Church in the Middle Ages. It was by far the strongest force in the history of those ages of faith, and it did more than anything else to civilize Europe after the migrations of the Barbarians. Throughout the length and breadth of Europe, bishops in their dioceses, priests in their parishes, and monks in their monasteries, held all the people in the bonds of Holy Church.
Christian missionaries went into every land to preach the Gospel and civilize the people: St. Patrick (about 450) in Ireland; St. Columba (563), and later St. Aidan, in Iona and Lindisfarne; St. Augustine (596) in England; Irish missionaries in Italy; St. Boniface from England (c. 750) in Germany; while the Eastern or "Orthodox" Church converted the Russians and other Slavs.
Monasteries were built in every land, and they contained the schools and hospitals and inns, the best farms and dairies of the Middle Ages. The monastic buildings included the church; the dormitory and refectory where the monks slept and dined; the hospital, the kitchen, and the scriptorium or writing-place. All were built round a great open court or cloister-garth, and surrounded by a high wall.
The Bishop of Rome had become the Father, or Pope, of the Church, and had gained great influence during the barbarian invasions. It was Leo the Great who saved Rome from the terrible Attila the Hun (453), and another Pope saved the Romans from the equally terrible Vandals (455).
Gradually the Popes claimed powers equal, and even superior, to the Emperors. Gregory VII, or Hildebrand, one of the greatest of Popes, reigned at the time his friend William the Conqueror was making England his own. Hildebrand's great aim was to make the papacy supreme over all other Powers in Christian Europe. To make kings and princes obey him, he threatened to cut them off from all the Church services -- that is, to excommunicate them.
In order to make the Church quite independent, he forbade the clergy to receive the signs of their office (the ring and staff) from princes, and this led to a long and bitter struggle between Church and State. This was a cause of Henry I's quarrel with Anselm; while Henry II's policy of bringing all his people -- lay and cleric -- under his control was the cause of his struggle with Becket.
So implacable was the Pope that he made even the emperor (Henry IV) stay bare-footed in the snow for three days and nights outside the castle of Canossa in Italy (1077), before he would receive him. Hildebrand was one of the strongest figures of the Middle Ages.