Charlemagne may have called his empire Roman for the sake of tradition, but the essential factor was its Christianity. His coronation by the pope in Saint Peter’s sealed the alliance between the Carolingians and the church (the “rule by the grace of God”), first formed by Pepin the Short.
Charlemagne’s military conquests brought most of western Europe under one rule. His empire reached from the Elbe and Danube rivers to the Atlantic Ocean. It included a part of northern Spain and most of the Italian peninsula. The king was not satisfied, however, merely to exact tribute from the conquered territories and to tap their resources as other emperors had done.
The militant Christianity of the Frankish ruler impelled him to stamp out pagan practices wherever he encountered them, and consequently his victories usually preceded a thorough – and often harsh – religious and social reform. He defiled the sacred shrines of the Saxons, for example, and did not hesitate to massacre thousands who refused to convert. Elsewhere, he practiced widespread deportation of those who balked at paying homage to a new god.
Despite the violence which often accompanied these forced conversions, Charlemagne’s policy had the long-term effect of uniting Europe. After his death, his weaker successors would not be able to hold his territory together, and the empire would split into smaller kingdoms. The religious unity would remain, however. It is a direct legacy of Charlemagne’s rule that Europe is a Christian continent.