Margrethe I, who had married in 1363, at the age of 10 and given birth to Oluf at 17, knew what she was doing.
With Denmark under Oluf’s little belt and the Norwegian crown bound to follow in due course, she encouraged him to think of himself as “the true heir to Sweden” as well, a presumption that infuriated Albrecht, the reigning king of Sweden. 
Nevertheless, Margrethe had to think again when Oluf died at 17. While personally keeping the Danish throne warm, she persuaded the Norwegian nobility to recognize her grandnephew Erik of Pomerania as Oluf’s successor.
Erik, too, was five at this turning point in his career. Margrethe went behind Albrecht’s back to offer the Swedish nobles perpetual rights to their property ab privileges in exchange for their support against him.
Albrecht could take no more. Raising an army of German mercenaries, he demanded satisfaction at Falköping. A chronicler was surprised by the outcome: “God gave an unexpected victory into the hands of a woman.”
The Danish queen Margrethe’s grand scheme was at last realized at Kalmar in 1397 when Erik, now 14, donned the three crowns of Norway, Denmark and Sweden. “Rash, violent and obstinate,” he faced the tall order of running an empire from the Arctic Circle (including Swedish Finland) to the Eider, and west to Greenland, with no money or support from the wary nobility.
Margrethe had her hands full nursing the damage caused by Erik’s railings against these constraints, and she was addressing the aftermath of a war with Holstein when she collapsed.
The Danish nobility wondered aloud whether their interests might be better served by Erik’s nephew, Christopher of Bavaria, and the talk in Sweden was of a separate constitution and a fresh crowned head.
Meanwhile, Erik retired to Visborg Castle in Gotland and applied himself, privately and very profitably, to the business of piracy.
Feature image (on top) Erik of Pommern crowned to King of Denmark, Norway and Sweden June 17, 1397 at Kalmar Castle.