Heimskringla: The Chronicle of the Kings of Norway

Halfdan the Black got a wife called Ragnhild, a daughter of Harald Gulskeg (Goldbeard), who was a king in Sogn. They had a son, to whom Harald gave his own name; and the boy was brought up in Sogn, by his mother’s father, King Harald. Now when this Harald had lived out his days nearly, and was become weak, having no son, he gave his dominions to his daughter’s son Harald, and gave him his title of king; and he died soon after. The same winter his daughter Ragnhild died; and the following spring the young Harald fell sick and died at ten years of age. As soon as Halfdan the Black heard of his son’s death, he took the road northwards to Sogn with a great force, and was well received. He claimed the heritage and dominion after his son; and no opposition being made, he took the whole kingdom. Earl Atle Mjove (the Slender), who was a friend of King Halfdan, came to him from Gaular; and the king set him over the Sogn district, to judge in the country according to the country’s laws, and collect scat upon the king’s account. Thereafter King Halfdan proceeded to his kingdom in the Uplands.

In autumn, King Halfdan proceeded to Vingulmark. One night when he was there in guest quarters, it happened that about midnight a man came to him who had been on the watch on horseback, and told him a war force was come near to the house. The king instantly got up, ordered his men to arm themselves, and went out of the house and drew them up in battle order. At the same moment, Gandalf’s sons, Hysing and Helsing, made their appearance with a large army. There was a great battle; but Halfdan being overpowered by the numbers of people fled to the forest, leaving many of his men on this spot. His foster-father, Olver Spake (the Wise), fell here. The people now came in swarms to King Halfdan, and he advanced to seek Gandalf’s sons. They met at Eid, near Lake Oieren, and fought there. Hysing and Helsing fell, and their brother Hake saved himself by flight. King Halfdan then took possession of the whole of Vingulmark, and Hake fled to Alfheimar.