As with most heathen religions that of the Northmen was full of terrors. Their lively imagination peopled the world with many strange figures. Fiends and monsters inhabited the marshes, giants lived in the dark forest, evil spirits haunted all solitary places, and ghosts stalked over the land by night. The use of charms and spells to guard against such creatures passed over into Christian times. Their memory also survives in folk tales, which are full of allusions to giants, dwarfs, goblins, and other supernatural beings. CHRISTIANIZATION OF THE NORTHMEN Christianity first gained a foothold in Denmark through the work of Roman Catholic missionaries sent out by Charlemagne's son, Louis the Pious. [8] Two centuries elapsed before the Danes were completely converted. From Denmark the new faith spread to Sweden. Norway owed its conversion largely to the crusading work of King Olaf (1016-1029 A.D.), whose zeal for Christianity won him the title of Olaf the Saint. The Norwegians carried Christianity to Iceland, where it supplanted the old heathenism in the year 1000 A.D. With the general adoption of the Christian religion in Scandinavian lands, the Viking Age drew to an end. [Illustration: NORSE METAL WORK (Museum, Copenhagen) A door from a church in Iceland; date, tenth or eleventh century. The iron knob is inlaid with silver. The slaying of a dragon is represented above and below is shown the Midgard serpent.] 141. THE NORTHMEN IN THE WEST CAUSES OF THE VIKING MOVEMENT The Northmen were still heathen when they set forth on their expeditions of plunder and conquest. Doubtless the principal cause of this Viking movement is to be sought in the same hunger for land which prompted the Germanic invasions and, in fact, has led to colonial expansion in all ages. By the ninth century Scandinavia could no longer support its rapidly growing population, and enforced emigration was the natural consequence. The political condition of Scandinavia at this time also helps to explain the Viking expansion. Denmark and Norway had now become strong kingdoms, whose rulers forced all who would not submit to their sway to leave the country. Thus it resulted that the numbers of the emigrants were swelled by exiles, outlaws, and other adventurers who turned to the sea in hope of gain. RAIDS OF THE NORTHMEN The Northmen started out as pirates and fell on the coasts of England, France, and Germany. In their shallow boats they also found it easy to ascend the rivers and reach places lying far inland. The Northmen directed their attacks especially against the churches and monasteries, which were full of treasure and less easily defended than fortified towns. Their raids inspired such great terror that a special prayer was inserted in the church services: "From the fury of the Northmen, good Lord, deliver us." THE NORTHMEN IN IRELAND, SCOTLAND, AND THE ISLANDS