Halfdan was a year old when his father was killed, and his mother Asa set off immediately with him westwards to Agder, and set herself there in the kingdom which her father Harald had possessed.
Halfdan grew up there, and soon became stout and strong; and, by reason of his black hair, was called Halfdan the Black. When he was eighteen years old he took his kingdom in Agder, and went immediately to Vestfold, where he divided that kingdom, as before related, with his brother Olaf. The same autumn he went with an army to Vingulmark against King Gandalf.
They had many battles, and sometimes one, sometimes the other gained the victory; but at last they agreed that Halfdan should have half of Vingulmark, as his father Gudrod had had it before. Then King Halfdan proceeded to Raumarike, and subdued it.
King Sigtryg, son of King Eystein, who then had his residence in Hedemark, and who had subdued Raumarike before, having heard of this, came out with his army against King Halfdan, and there was great battle, in which King Halfdan was victorious; and just as King Sigtryg and his troops were turning about to fly, an arrow struck him under the left arm, and he fell dead.
Halfdan then laid the whole of Raumarike under his power. King Eystein's second son, King Sigtryg's brother, was also called Eystein, and was then king in Hedemark. As soon as Halfdan had returned to Vestfold, King Eystein went out with his army to Raumarike, and laid the whole country in subjection to him.