All 21 wars between Denmark and Sweden (1205-1814)

1205-1210: The Danes support Sverker Karlsson (Sverkerska) in his fight with Erik Knutsson (Erikska) over the Swedish throne.

1360-1361: The Danish King Valdemar Atterdag captures Skåne, Halland, Blekinge and Gotland.

1389-1398: King Albrekt of Sweden and his supporters are defeated by the forces of the nobility and Queen Magrethe of Denmark and Norway and the Kalmar Union comes into existance.

1434-1436: A revolt led by Engelbrekt Engelbrektsson leads to the first estates parliament in Sweden to declare King Erik of Denmark, Norway and Sweden deposed as King of Sweden.

1448-1450: As King Kristoffer dies suddenlly, the estates parliament elect the Swedish prominent nobleman Karl Knutsson (Bonde) King of Sweden. Both he an King Kristian I of Denmark are elected King of Norway by their respective supporters and war breaks out over Norway.

1452-1457: War between King Karl Knutsson (Bonde) and King Kristian of Denmark.

1463-1471: Since King Karl Knutsson (Bonde) had returned as King, new fighting broke out as King Kristian tried to enforce his claims to the Swedish throne.

1501-1520: Sten Gustavsson (Sture), having been deposed by Swedish supporters of the Kalmar Union 1497 returns and revolts against King Hans of Denmark. This is what leads to Stockholm’s bloodbath

1521-1523: Gustav Eriksson (Wasa) leads a rising against King Kristian II and finally ends the Kalmar Union.

1534-1536: Sweden intervenes in the Counts’ feud in Denmark to ensure that King Kristian II can not regain the throne in Denmark.

1563-1570: The Nordic Seven Years’ War between Denmark and Sweden.

1611-1613: The Kalmar War between Denmark and Sweden.

1643-1645: Torstensson’s War between Denmark and Sweden.

1657-1658: Karl X Gustav’s War between Denmark and Sweden.

1658-1660: Karl X Gustav’s second War between Denmark and Sweden.

1675-1679: The Scanian War between Denmark and Sweden.

1700: First Danish participation in the Great Nordic War. 

1709-1719: Second Danish participation in the Great Nordic War.

1788-1790: The teather war. Sweden attack Russia, and Denmark honours its alliance with Russia and declares war.

1808-1809: The Danish war. Denmark, allied with Russia, which prodded by Napoleon attacks Sweden to force it into the continental system, declares war on Sweden.

1814: The invasion of Norway. (Denmark had to give Norway to Sweden)

(Source:  vonadler)