How central Europe, attacked from sides, become an armed camp and why Europe would have perished without those professional soldiers and administrators who were part of the feudal system

The following, then, is the state of Europe in the year one thousand, when most people were so unhappy that they welcomed the prophecy foretelling the approaching end of the world and rushed to the monasteries, that the Day of Judgement might find them engaged upon devout duties.

At an unknown date, the Germanic tribes had left their old home in Asia and had moved westward into Europe. By sheer pressure of numbers they had forced their way into the Roman Empire. They had destroyed the great western empire, but the eastern part, being off the main route of the great migrations, had managed to survive and feebly continued the traditions of Rome's ancient glory.

During the days of disorder which had followed, (the true "dark ages"of history, the sixth and seventh centuries of our era,) the German tribes had been persuaded to accept the Christian religion and had recognised the Bishop of Rome as the Pope or spiritual head of the world. In the ninth century, the organising genius of Charlemagne had revived the Roman Empire and had united the greater part of western Europe into a single state. During the tenth century this empire had gone to pieces. The western part had become a separate kingdom, France. The eastern half was known as the Holy Roman Empire of the German nation, and the rulers of this federation of states then pretended that they were the direct heirs of Ceasar and Augustus.