Kalmar Union

History of Denmark between 1397 - 1522

The most important aspect of the Kalmar Union was the personal union between the three kingdoms of Denmark, Norway and Sweden. Also included in this fellowship was Finland, that was a part of Sweden (until 1809), and Iceland, Greenland, the Faroes and the Shetland archipelago, belonging to Norway, meaning that the union encompassed all of the Nordic countries. The formal marking of the unification took place in the Swedish city of Kalmar, where Erik of Pomerania was crowned king of all three realms in 1397. The union’s centre of power was located in Denmark, but all the countries were principally ruled according to their own laws and traditions.

The creation of the Kalmar Union

Kalmar Slott Aug2011
The union was formed in Kalmar Castle
Before the creation of the Kalmar Union, as well as the crowning of Erik of Pomerania as the king of Denmark, Norway and Sweden in 1397, Margrethe I had fought since 1375 to seize the power in Denmark, and later on in the two other kingdoms. She managed – despite strong competition – to claim the crown of Denmark and later on the true power over the country for her son, Oluf, in the period of 1375-1385. In 1380 her husband, King Haakon VI of Norway, died, after which their son inherited the throne of Norway. After Oluf’s death in 1387, Margrethe managed to become ruler of both Denmark and Norway, and soon she allied herself with important parts of the Swedish aristocracy against the German king of Sweden, Albrecht of Mecklenburg. The decisive blow in the battle for the Swedish crown came in 1389, when King Albrecht and his son were captured. After this, it can be said that the Kalmar union was in reality established, even though Margrethe at the time had yet to capture Stockholm as well as a few other Swedish territories.

The troubles of Erik of Pomerania

Eric Pomeranian Statue 20101023
Eric of Pomerania statue
at Darlowo Castle
When Margrethe I died in 1412, the stage was finally set for Erik of Pomerania. He ‘inherited’ a conflict with the dukes of Holstein centred on the power over the Danish duchy of Schleswig. This conflict eventually took a catastrophic turn for the king of the three realms, especially because the Hanseatic towns gradually joined the Holstein cause. Even though Erik of Pomerania did well in the fight war against the Hanseatic towns, it was probably the financial support they lent to Holstein that turned the battle against Erik of Pomerania. In the end, he was forced to leave most of Schleswig to Holstein in 1432.

In connection with his wars, Erik of Pomerania had also drafted soldiers and raised taxes in Sweden and Norway. This lead to a peasant rebellion in Sweden in 1434, which quickly gained support from the Swedish aristocracy. In 1436, a similar uprising took place around Oslo in Norway. The consequence of this would be assorted standstills, agreements and new uprisings, which eventually culminated in Erik of Pomerania being deposed as king of Denmark and Sweden in 1439. Before this, a massive peasant rebellion had also broken out in Denmark.

His nephew, Christoffer of Bavaria, who in the period from 1440 to 1442 managed to become king of all three realms, succeeded Erik. This would be the end of the strongly centralised government that Margrethe and Erik had maintained during their reigns. The Councils of the Realms in the individual countries had been responsible for this change in king, and thus increased the own power afterwards.

The battles for Sweden

Christoffer of Bavaria died at an early age in 1448, leaving no children. Afterwards, the Swedes elected the Swedish magnate Karl Knutsson as king, while Denmark chose a distant relative of the Danish kings, Christian of Oldenburg. Following this, a race began to claim the crown of Norway, which Christian I won in 1450. A few years later, Christian managed to take advantage of an internal disagreement in Sweden to become the king of Sweden in 1457. However, his reign there would only last until 1464, where he was deposed and Karl Knutsson returned. After Knutsson’s death in 1470, Christian I made another ambitious attempt to claim the Swedish crown, but suffered an ignominious defeat at the Battle of Brunkeberg in 1471.

Christian had made sure that his own son, Hans, would be his successor in all three kingdoms. After Christian’s death in 1481, protracted negotiations began about the terms of Hans’s kingship of the three realms. When all the details had been agreed upon, however, the Swedes bailed at the last minute, meaning that Hans had to settle for becoming king of only Denmark and Norway in 1483. In 1497, the Swedish aristocracy was again in disagreement, which Hans used to become king of Sweden. It would only be four years, however, before he was deposed in 1501.

The final days of the Kalmar Union

The final attempt at sustaining the Kalmar Union was made by King Hans’s son, Christian II, who became king of Denmark and Norway in 1513. His ambition was to strengthen the Royal power and reclaim Sweden, which – after yet more internal disagreements in Sweden – he succeeded at in 1520. Shortly after Christian II’s festive crowning ceremony, the Stockholm Bloodbath was carried out, killing 82 former enemies of Christian II. If Christian II believed that this would crush all future Swedish resistance against him, he would be sorely disappointed; on the contrary, the bloodbath led to a rebellion, and the year after, in 1521, Christian’s reign over Sweden ended. The rebellion was led by the Swedish magnate Gustav Vasa, who was crowned king of Sweden in 1523.

This signalled the end of the Kalmar Union, as well as the king’s fall in Denmark and Norway the same year. Christian II was deposed and replaced by his uncle, Frederik I. He, as well as Gustav Vasa of Sweden, feared that Christian’s powerful brother-in-law, Emperor Charles V, would put him back into power. Thus, the following years were characterised by a relative peace between the two countries, which in time would be called archenemies.


The Kalmar Union was caused by the inability of the three old Nordic royal families to produce more than one acceptable candidate at a time, coupled with the persistently rebellious nature of the Swedish magnates during the 14th century. During the 1400s, it became obvious, that this rebelliousness was a symptom of factions vying for power in Sweden. A number of Swedish magnates, due to connections through marriage and inheritances in several countries, had a vested interest in maintaining the Nordic personal union, while others sometimes saw an advantage in supporting the Danish kings in order to further their own positions in the power struggles. However, the dominant school of thought seems to have been that a personal union without a king provided the best opportunity for not having to share the power with a king. Therefore, the basic idea of the union persisted for so long.

References: Aarhus Universitet - Institut for Kultur og Samfund

Previous historical period: The First Kingdom (1036-1396) | Next historical period: Early Modern Denmark (1523-1658)

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