Denmark has dominion over the strait between the Baltic Sea and the North Sea.

Sweden seeks an alternative trade route to avoid paying Denmark's Sound Toll through northern Norway, and seeks control the land route through sparsely populated Lapland.

In 1607, Charles IX of Sweden had declared himself "King of the Lapps in Nordland" and had begun “collecting” taxes in Norwegian territory, even south of Tromsø.Since Sound Dues to pass through the strait between the Baltic and the North Sea are Denmark's main source of income, Denmark does not want alternative trade routes established, particularly when established through Norwegian territory.

Denmark protests.King Charles IX of Sweden ignores the protests of King Christian IV of Denmark and Norway.

Finally, in 1611 in response to Sweden's claim of a traditionally Dano-Norwegian area in Northern Norway, Denmark invades Sweden.