The barons, who had acquired extensive privileges during the reign of King Magnus, had a chance to establish their power still more securely during the minority of his son Erik, who, at his father's death, was but twelve years old. A great influence was also wielded by the imperious queen-dowager, Ingeborg, who made common cause with the barons and was the real soul of the regency. Of her two surviving sons, Duke Haakon, the younger, was the more fitted, by strength of body and mind, to occupy the throne. He received great fiefs, and though recognizing Erik's overlordship, conducted himself as an independent sovereign. He issued decrees, coined money, and made independent alliances with foreign princes. His brother was a weak, good-natured man who never knew how to assert his will against that of his mother and his high-handed councillors. The latter, among whom the barons, Hallkell Agmundsson, Audun Hugleiksson, and Bjarne Erlingsson of Giske and BjarkÖ, were the most eminent, disapproved highly of the concessions which King Magnus had made to the Church, and were watching for an opportunity to check the power and arrogance of the clergy. They found it necessary, however, to conceal their plans, until the king had been crowned by Archbishop Jon, and they even consented to have him include in the coronation oath the promise "to yield all due honor to the clergy and the bishops, and to repeal all bad laws, especially such as might conflict with the liberty of the Church."

The archbishop interpreted this promise literally, and demanded after the coronation the repeal of the laws in question. The queen and the barons were, however, not disposed to yield a single point, but rather welcomed the opportunity to measure strength with the domineering prelates. It was of no use that the archbishop put Hallkell Agmundsson in the ban; his colleagues only honored him more conspicuously, and when Queen Ingeborg and Bjarne Erlingsson received the same punishment, they, as well as the people, showed an indifference, which left the archbishop powerless. After having vainly appealed to the Pope, and having been foiled at the Roman Curia by ambassadors from the barons, Jon the Red and two other bishops were outlawed and compelled to leave the country. The archbishop died in exile in Sweden in 1282.

The king, who was yet a mere boy, was neutral in this struggle. If the decision had rested with him, he would probably have continued his father's policy of concession, and the epithet "Priest-Hater," which has been attached to his name, is therefore undeserved.

When Erik was fourteen years old, he was married to Margaret of Scotland, the daughter of his grandfather's enemy, King Alexander III. The young queen died, however, a year later, after having given birth to a daughter, who, on the death of King Alexander (1284), was acknowledged as the heir to the throne of Scotland. While yet a child (1290), the Maid of Norway, as she was called, embarked for the land which she was to rule, but died before reaching it. Her father then, as his daughter's heir, laid claim to the Scottish crown, but the armed interference of King Edward I. of England compelled him to abandon his candidacy. He had at that time another controversy on his hands, which threatened serious results.

The queen-dowager, Ingeborg, was the daughter of the Danish king, Erik Plowpenny. His nephew, Erik Glipping, who succeeded his father, Christopher I., refused to surrender her inheritance, which consisted in landed estates in different parts of the kingdom. Magnus Law-Mender had vainly insisted upon the surrender of the property, and Erik, at the instigation of his mother, resumed negotiations, and, when these resulted in nothing, made threatening demonstrations. The Norse baron, Sir Alf Erlingsson, a special favorite of the queen, began to prey upon the shipping in the Sound, and by his recklessness and daring, made his name dreaded among seamen and merchants. He did, indeed, inflict much injury upon Danish commerce, and ravaged the coasts of Jutland and Halland; but the principal sufferers were the cities of the Hanseatic League, which, by the concessions of Magnus Law-Mender, had obtained a virtual monopoly of the foreign trade of Norway. Their ships were now seized without mercy by the noble pirate, who added insult to injury by once appearing incognito among them in an open boat, and bargaining with them about the price which they had set upon his head. It was of no use that the League sent out ships of war to capture him; he out-manoeuvred them, deceived them, sent them on a wild-goose chase, and ended by capturing his would-be captors. Though not officially authorized to carry on war in this fashion, Sir Alf perceived that his performances were winked at by the queen-dowager, who was actually so gratified at his success, that she had him created an earl, and induced the king to use him as his ambassador to England. As allies of the King of Denmark, the Hanseatic cities were, in the queen's opinion, entitled to no consideration, but she forgot in her blind hostility that they had it in their power to take revenge. Partly on account of the risk, partly as a measure of retaliation, the Hansa forbade the importation of grain and other staples of food to Norway, and the result was famine and misery. The hostilities with Denmark in the meanwhile continued, but were, after the death of Queen Ingeborg (1287), conducted, not by piracy, but by open warfare. A conspiracy was formed against the life of King Erik Glipping, and he was murdered, while on the chase (1286), by Marshal Stig, Count Jacob of Halland, and others. The murderers, who were outlawed in Denmark, found a refuge in Norway, and accompanied King Erik on his campaign against their native country in 1289. The city of Elsinore was burned, and the Norwegian fleet lay for four weeks near Copenhagen, serving as a basis of operations for the outlawed king-slayers, who satisfied their private vengeance by burning cities and castles. Three similar expeditions, during the following six years, brought Erik neither honor nor profit in proportion to the cost of the enterprise; although, in the end, the Danish king, Erik Menved, was compelled to conclude an armistice for three years at Hinsgavl, in Funen (1295), at which he made a definite promise of the surrender of the disputed property. The king-slayers were permitted to return unmolested to their homes, and their estates were to be restored to them.

The war with the Hanseatic cities had come to an end long before, by the peace of Kalmar, (1285). The formidable weapon which they wielded, in their ability to cut off supplies, gave them so great an advantage that King Erik had no choice but to accept their terms. King Magnus of Sweden, who, according to mutual agreement, had been selected as umpire negotiated peace, on the conditions that King Erik should return to their owners all ships which had been captured, pay an indemnity of six thousand marks and greatly extend the commercial privileges of the Hansa. Thus the lawless valor of "Little Sir Alf," as the pirate earl was called, proved no less disastrous to his country than it did to himself. He did not appreciate the difference which the death of the queen had made in his position; but continued to tread law and honor under foot with defiant heedlessness. The baron, Sir Hallkell Agmundsson the commander of Oslo Castle, had for some reason incurred his hostility; and Earl Alf gathered, in the ancient fashion, a band of adventurers about him and commenced a rebellion, as it appears, against Duke Haakon, who was Sir Hallkell's protector. He even had the audacity to attack Oslo, set fire to the town, capture his foe, and after a brief imprisonment executed him. This daring murder brought upon him a sentence of outlawry; and he was forced to seek refuge in Sweden, where King Magnus took him under his protection. His luck had, however, deserted him, for when again he appeared as a corsair in Danish waters, he was captured and brought in irons into the presence of Queen Agnes. According to the ballad, she twitted him on the smallness of his stature; to which he replied that she would never live to see the day when she could bear such a son. Another and still more insolent remark made the queen so furious that she struck her fist against the table and declared that Little Sir Alf should be tortured on the rack, and his bones broken on the wheel. The sentence was executed the following day (1290).

After the death of his first queen, King Erik had married Isabella Bruce, the sister of Robert, who later became King of Scotland. He had by this marriage a daughter, Ingeborg, who became the wife of Duke Valdemar, the brother of the Swedish king, Birger Magnusson. King Erik died at the age of thirty-one (1299), after having been king for nineteen years.