I will put in the form of a category or list the chief points which we must bear in mind.
In the first place the Dark Ages were a period of intense military action. Christendom was besieged from all around. It was held like a stronghold, and in those centuries of struggle its institutions were molded by military necessities: so that Christendom has ever since had about it the quality of a soldier. There was one unending series of attacks, Pagan and Mohammedan, from the North, from the East and from the South; attacks not comparable to the older raids of external hordes, eager only to enjoy civilization within the Empire, small in number and yet ready to accept the faith and customs of Europe. The barbarian incursions of the fifth and sixth centuries—at the end of the United Roman Empire—had been of this lesser kind. The mighty struggles of the eighth, ninth and especially the tenth centuries—of the Dark Ages—were a very different matter. Had the military institutions of Europe failed in that struggle, our civilization would have been wiped out; and indeed at one or two critical points, as in the middle of the eighth against the Mohammedan, and at the end of the ninth century against the northern pirates, all human judgment would have decided that Europe was doomed.
In point of fact, as we shall see in a moment, Europe was just barely saved. It was saved by the sword and by the intense Christian ideal which nerved the sword arm. But it was only just barely saved.
The first assault came from Islam.
A new intense and vividly anti-Christian thing arose in a moment, as it were, out of nothing, out of the hot sands to the East and spread like a fire. It consumed all the Levant. It arrived at the doors of the West. This was no mere rush of barbarism. The Mohammedan world was as cultured as our own in its first expansion. It maintained a higher and an increasing culture while ours declined; and its conquest, where it conquered us, was the conquest of something materially superior for the moment over the remaining arts and traditions of Christian Europe.
Just at the moment when Britain was finally won back to Europe, and when the unity of the West seemed to be recovered (though its life had fallen to so much lower a plane), we lost North Africa; it was swept from end to end in one tidal rush by that new force which aimed fiercely at our destruction. Immediately afterwards the first Mohammedan force crossed the Straits of Gibraltar; and in a few months after its landing the whole of the Spanish Peninsula, that strong Rock as it had seemed of ancient Roman culture, the hard Iberian land, crumbled. Politically, at least, and right up to the Pyrenees, Asia had it in its grip. In the mountain valleys alone, and especially in the tangle of highlands which occupies the northwestern corner of the Spanish square, individual communities of soldiers held out. From these the gradual reconquest of Spain by Christendom was to proceed, but for the moment they were crowded and penned upon the Asturian hills like men fighting against a wall.
Even Gaul was threatened: a Mohammedan host poured up into its very centre far beyond Poitiers: halfway to Tours. Luckily it was defeated; but Moslem garrisons continued to hold out in the Southern districts, in the northern fringes of the Pyrenees and along the shore line of the Narbonese and Provence.
Southern Italy was raided and partly occupied. The islands of the Mediterranean fell.
Against this sudden successful spring which had lopped off half of the West, the Dark Ages, and especially the French of the Dark Ages, spent a great part of their military energy. The knights of Northern Spain and the chiefs of the unconquered valleys recruited their forces perpetually from Gaul beyond the Pyrenees; and the northern valley of the Ebro, the high plains of Castile and Leon, were the training ground of European valor for three hundred years. The Basques were the unyielding basis of all the advance.
This Mohammedan swoop was the first and most disastrously successful of the three great assaults.