Sweden and Denmark have a long and rather unhealthy history of settling disagreements.

For centuries, the two kingdoms fought over land, trade, the Baltic Sea, Norway, and—apparently—the fundamental question of who was allowed to be the most important Scandinavian country.

There is no single agreed number of wars between them, because medieval rebellions and different phases of larger conflicts can be counted in different ways. But once you include the medieval conflicts and the later wars, the list becomes remarkably long. From the major wars of 1563 to 1720 alone, there were seven major Danish-Swedish war periods.

⚔️ The Viking Age – when diplomacy meant bringing more Vikings

The rivalry goes back long before either country looked anything like the modern Sweden or Denmark.

During the Viking Age, Danish and Swedish rulers competed for influence over Scandinavia and the Baltic. Raids, alliances, trade and outright warfare were all part of the political toolkit.

The historical record becomes increasingly reliable as we approach the Middle Ages, but Scandinavian sagas also preserve stories of much earlier Swedish-Danish wars—some of which are difficult to separate from legend.

Basically, the Scandinavian diplomatic system was:

"Nice kingdom you've got there. Would be a shame if something happened to it."

👑 The Kalmar Union – Denmark discovers the benefits of having Sweden as a friend

In 1397, Denmark, Norway and Sweden were brought together in the Kalmar Union, sharing a monarch.

On paper, this sounds like a brilliant Scandinavian cooperation project.

In practice, Sweden increasingly felt that Denmark was rather too enthusiastic about being in charge.

The following century saw repeated Swedish rebellions, Danish attempts to reassert control and several actual wars. Sweden gained and lost independence more than once during this period.

Eventually came Christian II, or in Sweden known as Kristian Tyrann (Christian the Tyrant).

Christian apparently preferred a fairly hands-on approach to keeping Sweden obedient. After the Stockholm Bloodbath of 1520, Swedish opinion of the Danish king declined somewhat.

Gustav Vasa subsequently led the Swedish War of Liberation, and in 1523 Sweden finally broke away from the Kalmar Union.

This time, Sweden meant it.

Sweden becomes a European great power

And this is where things become particularly interesting from the Swedish perspective.

After leaving the Kalmar Union, Sweden spent the following century becoming far more powerful than anyone might reasonably expect from a relatively small northern kingdom.

Swedish rulers increasingly focused on controlling the Baltic Sea. Sweden fought repeatedly with Denmark, Poland-Lithuania and Russia, while also becoming heavily involved in the Thirty Years' War.

Under Gustav II Adolf, Sweden became one of Europe's major military powers. Swedish intervention in the Thirty Years' War from 1630 onwards was remarkably successful, and Sweden emerged from the conflict as a major power in northern Europe.

And then came the really impressive part.

For a country with a relatively small population and a largely agricultural economy, this was an extraordinary achievement.

Sweden had effectively turned the Baltic Sea into its backyard.

And Stockholm wasn't even the only important centre. Riga, on the other side of the Baltic, was one of the empire's major cities. Swedish possessions stretched from Finland and the Baltic states to German territories and the Scandinavian peninsula.

For a brief period, Sweden wasn't just a Scandinavian power.

Sweden was the Scandinavian power.

Sweden 1658

🍺 And then there was Denmark, again.

Unfortunately for Denmark, Sweden's rise coincided with several more disagreements.

The Swedish victory in 1658 was particularly painful.

King Charles X Gustav launched an astonishing campaign across the frozen Danish straits. The Danish government was forced to negotiate, resulting in the Treaty of Roskilde.

Assault on Copenhagen, February 11, 1659. - Stormningen av Köpenhamn 11 feb. 1659

Denmark surrendered Scania, Blekinge, Halland and Bohuslän.

So, from the Swedish perspective:

Denmark had spent centuries trying to control Sweden.

Sweden eventually responded by taking a rather large chunk of Denmark.

Fair enough.

Denmark wasn't finished, however. It attempted to recover its lost territories during the Scanian War of 1675–1679.

It didn't work. Scania remained Swedish.

⚔️ One last round

The rivalry continued through the Great Northern War.

Denmark intervened against Sweden in 1700 and again from 1709 onward. Sweden ultimately lost its position as the dominant Baltic power during the war, and the final Danish-Swedish conflict ended with the Treaty of Frederiksborg in 1720.

And then there was Peace.

After centuries of invasions, rebellions, bloodbaths, sieges, frozen seas and arguments over who owned what, Sweden and Denmark apparently decided that perhaps this wasn't working.

So Denmark has never been Swedish, until now, in War Era, where it matters.