Erik was ultimately deposed from all three kingdoms of the union, but in 1449 he inherited one of the partitions of the Duchy of Pomerania and ruled it as duke until his death in 1459.

Named Bogusław (Bogislaw) at birth, he was the son of Wartislaw VII, Duke of Pomerania, and Maria of Mecklenburg-Schwerin.

Bogislaw's great-aunt Margaret I, who ruled the kingdoms of Denmark, Norway, and Sweden, wanted her realm to be unified and peaceful, and so made provisions in the event of her death.

[10][11] During the early period of his reign, King Erik made Copenhagen a royal possession in 1417, thereby assuring its status as the capital of Denmark.

Erik was described by the future Pope Pius II as having "a beautiful body, reddish yellow hair, a ruddy face, and a long narrow neck … alone, without assistance, and without touching the stirrups, he jumped upon a horse, and all women were drawn to him, especially the Empress, in a feeling of longing for love".

He tried to regain South Jutland (Schleswig) which Queen Margaret had been winning, but he chose a policy of warfare instead of negotiations.

The result was a devastating war that not only ended without conquests, but also led to the loss of the South Jutlandic areas that he had already obtained.

In 1424, a verdict of the Holy Roman Empire by Sigismund, King of Germany, recognising Erik as the legal ruler of South Jutland, was ignored by the Holsteiners.

To help enforce his demands, Erik built Krogen, a powerful fortress at the narrowest point in the Sound, in the early 1400s.

When the Hanseats and Holsteiners attacked Copenhagen in 1428, King Erik was absent from the city at Sorø Abbey and did not return, so Queen Philippa managed the defense of the capital.

In 1434, the farmers and mine workers of Sweden began a national and social rebellion which was soon used by the Swedish nobility in order to weaken the power of the King.

The rebellion caused erosion within the unity of the Kalmar Union, leading to the temporary expulsion of Danish forces from Sweden.

Under the terms of the peace agreement, Hanseatic cities were excepted from the Sound Dues and the Duchy of Schleswig was ceded to the count of Holstein.

[27] The Burgermeister of Kiel to King Christian III of Denmark wrote that Erik encouraged a joint expedition by Didrik Pining and Hans Pothorst to investigate the Northwest Passage.

[28] Erik's full title was: "King of Denmark, Sweden and Norway, the Wends and the Goths, Duke of Pomerania".