During the Napoleonic Wars until 1810, Sweden and the United Kingdom of Great Britain and Ireland were allies in the war against Napoleon. As a result of Sweden's defeat in the Finnish War and the Pomeranian War, and the following Treaty of Fredrikshamn and Treaty of Paris, Sweden declared war on the UK. The bloodless war, however, existed only on paper, and the UK was still not hindered in stationing ships at the Swedish island of Hanö and trade with the Baltic states.
Background
The Treaty of Paris, concluded on 6 January 1810, forced Sweden to join the Continental System, a trade embargo against the UK. Since the UK was Sweden's biggest trade partner this caused economic difficulties, and trade continued to take place through smuggling. On 13 November that year, France delivered an ultimatum to the Swedish government demanding that within five days Sweden:
- Declare war against the UK,
- Confiscate all UK ships in Swedish ports,
- Seize all UK products in Sweden.
France and its allies threatened to declare war against Sweden if it did not meet the French demands. On 17 November the same year, the Swedish government declared war against the UK.
War
No acts of war occurred during the conflict and the UK was even allowed to station boats in Hanö, thus "occupying" the island. Sweden did not try to hinder this as the UK used the island to continue trading with Sweden.
Aftermath
The elected crown prince of Sweden, Danish Prince Charles August, had died on 28 May 1810, and on 21 August 1810, the French Marshal Jean-Baptiste Bernadotte was elected crown prince of Sweden. Although Bernadotte was only the crown prince and technically subservient to King Charles XIII, the king's deteriorating health and disinterest made the crown prince the de facto ruler of Sweden. Under Bernadotte's rule, Sweden's relationship with Napoleonic France deteriorated. When France occupied Swedish Pomerania and the island of Rügen in 1812, Sweden sought peace with the UK.
After long negotiations, the Treaty of Örebro was signed on 18 July 1812. On the same day and at the same place, the UK and Russia signed a peace treaty to end the Anglo–Russian War (1807–1812).