They were Viking cruisers, on their way to plunder some coast town; and the old Emperor's prophecy was verified when the Norman, who was a civilized Norseman, became for a while the conquering race of Europe. Even before the death of Charlemagne the Norse and Danish sea-kings were raiding, plundering, and burning along the coasts of his Empire. Two hundred years of our own history is made up of the story of their incursions. England and Ireland bore the first brunt of their onset, when they found the ways of the sea. But they ravaged all the western coasts of Europe, and even showed themselves in the Mediterranean. From the end of the eighth till the beginning of the eleventh century they were the terror of the western world, and early in that dark and stormy period their raids had grown into great expeditions; they landed armies that marched far inland, and they carved out principalities for themselves. Western Europe had a brief respite at times when the Vikings fought amongst themselves. In early days there were frequent struggles for supremacy in Norway, between local kinglets and ambitious chiefs. Fighting was in the blood of the Northmen. Two sea-roving squadrons would sometimes challenge each other to battle for the mere sake of a fight. As Norway coalesced into a single kingdom, and as the first teachers of Christianity induced the kings to suppress piracy, there was more of peace and order on the Northern Seas. But in this transition period there was more than one struggle between the Scandinavian kingdoms, Norway, Sweden, and Denmark. One of the most famous battles of these northern wars of the sea-kings was fought in this period, when the old wild days of sea-roving were drawing to an end, and its picturesque story may well be told as that of a typical Norse battle, for its hero, King Olaf Tryggveson, was the ideal of a northern sea-king.