BATTLE BETWEEN HALFDAN AND EYSTEIN.
When King Halfdan heard of these disturbances in Raumarike, he again gathered his army together; and went out against King Eystein. A battle took place between them, and Halfdan gained the victory, and Eystein fled up to Hedemark, pursued by Halfdan. Another battle took place, in which Halfdan was again victorious; and Eystein fled northwards, up into the Dales to the herse Gudbrand. There he was strengthened with new people, and in winter he went towards Hedemark, and met Halfdan the Black upon a large island which lies in the Mjosen lake. There a great battle was fought, and many people on both sides were slain, but Halfdan won the victory. There fell Guthorm, the son of the herse Gudbrand, who was one of the finest men in the Uplands. Then Eystein fled north up the valley, and sent his relation Halvard Skalk to King Halfdan to beg for peace. On consideration of their relationship, King Halfdan gave King Eystein half of Hedemark, which he and his relations had held before; but kept to himself Thoten, and the district called Land. He likewise appropriated to himself Hadeland, and thus became a mighty king.
Heimskringla (c. 1225), by Snorri Sturluson [Snorre Sturlasson] (c.1179-1241)