When Harald Bluetooth died (985), his son Svein, who afterward was given the surname Tjuguskeg (Fork-beard), became king of Denmark. He instigated the Joms-vikings to make war on Earl Haakon. These vikings were Danes, who lived at Jomsborg, Pomerania, on the island Wollin or Jom, at the mouth of the river Oder. They were very powerful and warlike, and had very strict laws. No one could join their company who was older than fifty or younger than eighteen years, and no woman was permitted to enter their burgh. They considered it a disgrace to show fear or to complain of pain. Earl Sigvald (Sigvalde Jarl), a son of King Strut-Harald of Scania (Skaane, in the southern part of Sweden), was chief of the Joms-vikings at this time. King Svein of Denmark invited these vikings to a great feast in memory of his father, and as Earl Sigvald's father had fallen about the same time, he suggested that they should also drink his "funeral-ale." The Joms-vikings came to the festival with their bravest men, forty ships of them from Vendland (Pomerania), and twenty ships from Scania. All the guests drank a great deal, and there was great gayety in the hall. According to old custom on such occasions they made solemn vows, in emptying the drinking-horns. King Svein, in drinking to his father's memory, made the solemn vow, that before three winters were past he would go with his army to England and conquer King Ethelred. The guests also drank Christ's health, and a bowl to the memory of Saint Michael. Thereafter Earl Sigvald drank to his father's memory, and made a vow, that before three winters came to an end he would go to Norway and either kill Earl Haakon or chase him out of the country, and the other Joms-vikings vowed that they would go with Earl Sigvald to Norway and share in the fight. The next morning, when they had slept off their drink, they thought they had promised rather much, and, in order to find Earl Haakon unprepared, they sailed away on their expedition at once. When Earl Erik, the son of Haakon, who was then in Raumarike, heard of the festival and of the vows of the Joms-vikings, he immediately gathered his men, and went to the Uplands, and thence over the mountains to Throndhjem, and joined his father, Earl Haakon. They immediately sent warnings around, and sent messages to North More and South More, and to Raumsdal, and also north to Namdal and Halogaland, summoning all the country to furnish men and ships. Earl Haakon went with an army to South More, and Erik was to follow with what army he could collect from the north.