Gregory the Great was in Rome; here a town or a group of towns would be under the rule of the duke or prince of this or that. Amidst the vast ruins of the city of Rome half-independent families of quasi-noble adventurers and their retainers maintained themselves. The Pope kept a sort of general predominance there, but he was sometimes more than balanced by a "Duke of Rome." The great arena of the Colosseum had been made into a privately-owned castle, and so too had the vast circular tomb of the Emperor Hadrian; and the adventurers who had possession of these strongholds and their partisans waylaid each other and fought and bickered in the ruinous streets of the once imperial city. The tomb of Hadrian was known after the days of Gregory the Great as the Castle of St. Angelo, the Castle of the Holy Angel, because when he was crossing the bridge over the Tiber on his way to St. Peter's to pray against the great pestilence which was devastating the city, he had had a vision of a great angel standing over the dark mass of the mausoleum and sheathing a sword, and he had known then that his prayers would be answered. This Castle of St. Angelo played a very important part in Roman affairs during this age of disorder.
Spain was in much the same state of political fragmentation as Italy or France or Britain; and in Spain the old feud of Carthaginian and Roman was still continued in the bitter hostility of their descendants and heirs, the Jew and the Christian. So that when the power of the Caliph had swept along the North African coast to the Straits of Gibraltar, it found in the Spanish Jews ready helpers in its invasion of Europe. A Moslem army of Arabs and of Berbers, the nomadic Hamitic people of the African desert and mountain hinterland who had been converted to Islam, crossed and defeated the West Goths in a great battle in 711. In a few years the whole country was in their possession.
In 720 Islam had reached the Pyrenees, and had pushed round their eastern end into France; and for a time it seemed that the faith was likely to subjugate Gaul as easily as it had subjugated the Spanish peninsula. But presently it struck against something hard, a new kingdom of the Franks, which had been consolidating itself for some two centuries in the Rhineland and North France.
