Kalmar War

The Kalmar War (1611–1613) was a war between Denmark–Norway and Sweden. Though Denmark soon gained the upper hand, she was unable to defeat Sweden entirely. The Kalmar War was the last time Denmark successfully defended her dominium maris baltici against Sweden, and also marked the increasing influence of the Maritime Powers on Baltic politics.

Background
Since Denmark–Norway controlled the strait between the Baltic Sea and the North Sea, Sweden sought an alternative trade route through sparsely populated Lapland to avoid paying Denmark's Sound Dues. In 1607, Charles IX of Sweden declared himself "King of the Lapps in Nordland" and began “collecting” taxes in Norwegian territory, even south of Tromsø.

Since the Sound Dues were Denmark's main source of income, Denmark did not want to see alternative trade routes established, particularly when established through Norwegian territory. Denmark protested.

King Charles IX of Sweden ignored the protests of King Christian IV of Denmark and Norway. Finally, in April 1611, in response to Sweden's claim of a traditionally Dano-Norwegian area in Northern Norway, Denmark declared war upon Sweden and invaded.

The war's beginnings
The Danish side planned to attack Sweden on three fronts; from Kristianopel towards Kalmar, from Halmstad towards Jönköping and from Norway towards the fortress of Älvsborg and thereafter further into Västergötland.

A force of 6,000 men laid siege on the city of Kalmar, ultimately taking it. Norwegian forces, although stationed on the border, were instructed not to enter Sweden.

In the summer of 1611, Swedish forces under Baltzar Bäck were ordered to invade Norwegian Jämtland. They did so, and armed Swedish peasants marched into Härjedalen. Both Jämtland and Härjedalen were conquered without much fight. However, Bäck's lack of ability, or will, to stop excesses against the population meant that the locals eventually rose up against the Swedish occupants. In the end, the Swedish troops could not handle the situation and were forced to leave Jämtland/Härjedalen in the fall of 1612.

1612
On October 20 1611, King Charles IX of Sweden died and was succeeded by his son, Gustavus Adolphus. On ascending the throne, Gustavus Adolphus sued for peace, but Christian IV saw an opportunity for larger victories, and strengthened his armies in southern Sweden. In response, Gustavus began conducting raids along the border between Denmark and Sweden. In a February raid, Gustavus nearly drowned at the Battle of Vittsjö after being surprised by a Danish army.

In early 1612, Denmark attacked and eventually conquered two fortresses on the border between the fighting countries, Älvsborg and Gullberg, both in present-day Gothenburg. This was a major setback for Sweden, as the country now lacked access to the sea in the west. Having achieved this success, and aiming to end the war as soon as possible, the Danish command ordered an attack deep into Sweden, towards the capital of Stockholm. However, this proved to be a failure. Scorched earth methods and guerrilla warfare from the Swedish side made this a very difficult task and many of the mercenaries in the Danish army deserted since they did not receive their pay. Thus, the Danish army could never mount a serious attack on the capital itself.

Peace of Knäred
England and the Dutch Republic were also invested in the Baltic Sea trade, and pressured to curtail Denmark's power by ending the Kalmar War before a decisive victory could be attained. The Danes, while well-equipped and strong, had relied heavily on mercenary forces and Christian IV, low on funds, was finally amenable to persuasion in 1613. With the intercession of James I of England, the Treaty of Knäred was signed on January 20, 1613.

Denmark reached its victory, restoring Norwegian control of Sweden's land route through Lapland by incorporating Lapland into Norway (and thus under Danish rule). Further, Sweden had to pay a high ransom for two fortresses captured by Denmark. Sweden, however, achieved a major concession — the right of free trade through the Sound Strait, becoming exempt from the Sound toll.

In popular memory
Although a side-note to the war, the Battle of Kringen, in which Scottish mercenary forces were defeated by Gudbrandsdal militiamen from Lesja, Dovre, Vaage (Vågå), Fron, Lom and Ringebu is a noted military event in Norway, celebrated to this day.