Now, turn to your atlases again and look for the large island of Gotland off the south-eastern coast of Sweden, in the midst of the Baltic Sea. In the time of Olaf it was a thickly peopled and wealthy district, and the principal town, Wisby, at the northern end, was one of the busiest places in all Europe. To this attractive island the boy viking sailed with all his ships, looking for rich booty, but the Gotlanders met him with fair words and offered him so great a "scatt," or tribute, that he agreed not to molest them, and rested at the island, an unwelcome guest, through all the long winter. Early in the spring he sailed eastward to the Gulf of Riga and spread fear and terror along the coast of Finland. And the old saga tells how the Finlanders "conjured up in the night, by their witchcraft, a dreadful storm and bad weather; but the king ordered all the anchors to be weighed and sail hoisted, and beat off all night to the outside of the land. So the king's luck prevailed more than the Finlanders' witchcraft." Then away "through the wild sea" to Denmark sailed the young pirate king, and here he met a brother viking, one Thorkell the Tall. The two chiefs struck up a sort of partnership; and coasting southward along the western shores of Denmark, they won a sea-fight in the Ringkiobing Fiord, among the "sand hills of Jutland." And so business continued brisk with this curiously matched pirate firm--a giant and a boy--until, under the cliffs of Kinlimma, in Friesland, hasty word came to the boy viking that the English king, Ethelred "The Unready," was calling for the help of all sturdy fighters to win back his heritage and crown from young King Cnut, or Canute the Dane, whose father had seized the throne of England. Quick to respond to an appeal that promised plenty of hard knocks, and the possibility of unlimited booty, Olaf, the ever ready, hoisted his blue and crimson sails and steered his war-ships over sea to help King Ethelred, the never ready. Up the Thames and straight for London town he rowed. "Hail to the serpent banner! Hail to Olaf the Brave!" said King Ethelred, as the war-horns sounded a welcome; and on the low shores of the Isle of Dogs, just below the old city, the keels of the Norse war-ships grounded swiftly, and the boy viking and his followers leaped ashore. "Thou dost come in right good time with thy trusty dragon-ships, young King," said King Ethelred; "for the Danish robbers are full well entrenched in London town and in my father Edgar's castle." And then he told Olaf how, "in the great trading place which is called Southwark," the Danes had raised "a great work and dug large ditches, and within had builded a bulwark of stone, timber and turf, where they had stationed a large army." "And we would fain have taken this bulwark," added the King, "and did in sooth bear down upon it with a great assault; but indeed we could make naught of it." "And why so?" asked the young viking.