Sigurd was now sole king of Norway and free from the restraint which the pacific disposition of the popular Eystein had placed upon him. Shortly after the death of Eystein, King Sigurd entered into an agreement with the Danish king Nils Sveinson, who had married his stepmother, Margaret Fridkolla. They agreed upon a joint invasion of Sweden. The real motive was probably to secure this kingdom, which was at the time torn by internal strifes, for Margaret's son Magnus Nilson; but the avowed purpose was to christianize the inhabitants of the Swedish province of Smaaland, where paganism still lingered. The two kings were to meet with their armies at Oeresund. King Sigurd collected a fleet of about three hundred and sixty ships and proceeded to the meeting-place; but through some mistake the Danish army had already returned home. King Sigurd held a council with his men, at which they spoke of King Nils' breach of faith and determined to take revenge by plundering his country. They first plundered the town of Tumartorp, and then sailed east to the merchant town Kalmar, which they attacked. They plundered in the province of Smaaland, compelled the people to accept Christianity, and imposed on the country a tribute of 1,800 cattle. After this King Sigurd returned to Norway with a great booty. This expedition was called the Kalmar levy, and was the only levy Sigurd carried out while he was sole king. During the later years of his reign, King Sigurd was often violent and showed unmistakable signs of insanity. One Whit-Sunday he sat in his high-seat with Queen Malmfrid at his side, and in his hand he held the holy book, written in gilded letters, which he had brought with him from Constantinople. On the benches were seated many friends and guests. Then the king suddenly got one of his attacks. He rolled his eyes and looked all around him, and then said: "Many are the changes which may take place during a man's lifetime. Two things were dearer to me than anything else, namely, this book and the queen; and now it is quite different. The queen does not know herself how hideous she is; for a goat's horn is standing out of her head. And this book is good for nothing." Thereupon he threw the book on the fire which was burning on the floor, and gave the queen a blow with his fist between the eyes.