It was but a short time after the proclamation of Magnus as king that Harthaknut prepared to invade Norway. Magnus, who was eager to punish the race of Knut for their insidious plottings against his father, also made warlike preparations, apparently with the intention of invading Denmark. Whether any actual fighting took place is not known. It is not improbable that some insignificant skirmishing may have been done; but before any decisive battle was fought, the chieftains in both countries interfered and persuaded the two youthful combatants to make peace. At a meeting at the Brenn Islands, at the mouth of the Götha Elv, an agreement was made in accordance with which each made the other his heir and successor, in case he died, without issue (1038). This might, indeed, seem to be a remote contingency, but it actually came to pass four years later (1042) when Harthaknut died and Magnus was, without opposition, proclaimed king of Denmark at the Viborg-_thing_, and received the allegiance of the people. Thus Norway and Denmark were for the first time united, and the descendants of Harold the Fairhaired were recognized by the Danish branch of Ragnar Lodbrok's race as their equals, as they already had been recognized by the branch governing Sweden. Magnus must have been aware that it was to the sainthood of his father that he owed this recognition, and he lost no opportunity to show his reverence for his memory. He commenced the erection of a church in Nidaros, which was to bear St. Olafs name, and made him a new sarcophagus, adorned with gold and silver and precious stones. It was natural enough that he should take pleasure in the society of those who had been nearest to his father and stood at his side at Stiklestad. But the hostility aroused by the battle and the events that led to it existed, in some measure, yet; and one party began to fan the smouldering embers of distrust in the king's mind and incite him to vengeance against the other. Young as Magnus was, it is scarcely to be wondered at that he allowed himself to be influenced by this evil counsel. In spite of the amnesty which he had in Russia given to those who had borne arms against St. Olaf, he began now to punish all the leaders in the rebellion with great harshness. It was the Trönders, particularly, who had to bear the brunt of his wrath; because it was they who had made common cause with Knut and had been foremost in driving the sainted king into exile. Kalf Arnesson was among the first to experience the changed temper of King Magnus. Jealousies had early arisen between him and Einar Thambarskelver, both of whom called the king their foster-son and prided themselves on possessing his confidence. Once, it is said, Kalf had seated himself in Einar's seat next to the king, whereupon Einar sat down upon Kalf's shoulder, saying: "It behooves an old bull to be stalled before the calf."