The Northern peoples thus had a share in the fruitage of the later middle ages; but they also had a share in their achievements. Politically as well as intellectually the thirteenth century was a great age in the Scandinavian countries. The Danish kingdom rose to the highest point of its power under Valdemar the Victorious, whose troubled reign began in 1202. Valdemar succeeded in extending the territories of Denmark along the entire southern coast of the Baltic Sea; but the greatness was short-lived: after the defeat of the Danes by the North Germans at Börnhoved in 1227, the decline of Danish imperialism began. In Sweden, too, men dreamed of conquest beyond the sea. Under the leadership of Earl Birger, the most eminent statesman of medieval Sweden, Swedish power was steadily extended into Finnish territory, and the foundations of Sweden as a great European power was being laid.
During the days of Valdemar and the great Birger Norway also reached its greatest territorial extent. After a century of factional warfare, the nation settled down to comparative peace. All the Norwegian colonies except those in Ireland, were definitely made subject to the Norwegian crown: these were the Isle of Man, the Hebrides, the Orkneys, the Shetlands, the Faroes, Iceland, and Greenland. In every field of national life there was vigor and enterprise. And on the throne sat a strong, wise, and learned monarch, Hakon IV, the ruler with the “great king-thought.”
The real greatness of the thirteenth century in the North lies, however, in the literary achievements of the age. It is not known when the Old Norse poets first began to exercise their craft, but the earliest poems that have come down to us date from the ninth century. For two hundred years the literary production was in the form of alliterative verse; but after 1050 there came a time when scaldic poetry did not seem to thrive. This does not mean that the interest in literature died out; it merely took a new form: the age of poetry was followed by an age of prose. With the Christian faith came the Latin alphabet and writing materials, and there was no longer any need to memorize verse. The new form was the saga, which began to appear in the twelfth century and received many notable additions in the thirteenth. The literary movement on the continent, therefore, had its counterpart in the North; only here the writings took the form of prose, while there literature was chiefly in verse.