Margaret I, the daughter of Valdemar Atterdag, had found herself married off to Håkon VI of Norway in an attempt to join the two kingdoms, along with Sweden, since Håkon had kinship ties to the Swedish royal family.

The dynastic plans had called for her son, Olaf II to rule the three kingdoms, but after his early death in 1387 she took on the role herself (1387–1412).

During her lifetime (1353–1412) the three kingdoms of Denmark, Norway, and Sweden (including the Faroe Islands, as well as Iceland, Greenland, and present-day Finland) become linked under her capable rule, in what becomes known as the Kalmar Union, made official in 1397.