Though the prime characteristic of the Dark Ages is one of recollection, and though they are chiefly marked by this note of Europe sinking back into herself, very much more must be known of them before we have the truth, even in its most general form. 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.