The Story of Norway by Hjalmar Hjorth Boysen

Magnus Eriksson, the son of Duke Erik and Ingeborg, was only three years old when his grandfather died, and the government therefore fell into the hands of a regency, the members of which had already been designated by King Haakon. Shortly before, a rebellion had broken out in Sweden against King Birger, who, on account of the murder of his brothers, was detested by his people. He was deposed and his son Magnus, though he was in no wise responsible for his father's crimes, was executed. At the instance of the regent, Mats Kettilmundsson, Magnus Eriksson was proclaimed king; and Norway and Sweden were thus for the first time united under one ruler. The union was a mere nominal one, the two countries having separate laws and administrations, and nothing in common except the king, who was to divide his time equally between them.

During Magnus' minority, however, his mother, Duchess Ingeborg, governed in Norway with the utmost recklessness, making great scandal by her love of the Danish nobleman Knut Porse, duke of Halland, whom she later married. To enrich him she squandered the revenues and forfeited her popularity. When the treasury was on the verge of bankruptcy and loud murmurs of discontent were heard from all sides, the duchess was at last deprived of her power, and Sir Erling Vidkunsson of Bjarkoe and Giske was made regent in her place.