Russo-Swedish War (1808–1809)

The Finnish War (; ; ) was fought between the Kingdom of Sweden and the Russian Empire from 21 February 1808 to 17 September 1809 as part of the Napoleonic Wars. As a result of the war, the eastern third of Sweden was established as the autonomous Grand Duchy of Finland within the Russian Empire. Other notable effects were the Swedish parliament's adoption of a new constitution and the establishment of the House of Bernadotte, the new Swedish royal house, in 1818.

Background

After the Russian Emperor Alexander I concluded the 1807 Treaty of Tilsit with Napoleon, Alexander, in his letter on 24 September 1807 to the Swedish King Gustav IV Adolf, informed the king that the peaceful relations between Russia and Sweden depended on Swedish agreement to abide by the limitations of the Treaty of Tilsit which in practice meant that Sweden would have been required to follow the Continental System. The king, who viewed Napoleon as the Antichrist and Britain as his ally against Napoleon's France, was apprehensive of the system's ruinous consequences for Sweden's maritime commerce. He instead entered into negotiations with Britain in order to prepare a joint attack against Denmark, whose Norwegian possessions he coveted.

In the meantime, the Royal Navy attacked Copenhagen and the Anglo-Russian War (1807–1812) was declared. Referring to the treaties of 1780 and 1800, the emperor demanded that Gustav Adolf close the Baltic Sea to all foreign warships. Although he reiterated his demand on November 16, 1807, it took two months before the king responded that it was impossible to honor the previous arrangements as long as the French were in control of the major Baltic ports. King Gustav Adolf did this after securing an alliance with Britain on 8 February 1808. Meanwhile, on 30 December 1807 Russia announced it would be forced to act should Sweden not give a clear reply.

Although most Swedish officers were sceptical about their chances in fighting the larger and more experienced Imperial Russian Army, Gustav Adolf had an unrealistic view of Sweden's ability to defend itself against Russia. In Saint Petersburg, his stubbornness was viewed as a convenient pretext for Russia to occupy Finland, thus pushing the Russo-Swedish frontier considerably to the west of the Russian capital and safeguarding it in case of any future hostilities between the two powers.

The situation was problematic for Sweden, since it once again faced both Denmark and Russia as potential enemies requiring the Swedes to split their forces. The king had thought it impossible to defend Finland should the enemy attack during the winter and chose largely to ignore the repeated warnings of the Russian threat he received in early 1808. Most of the Swedish plans assumed that warfare would be impossible during winter, disregarding the lessons from recent wars. In addition, several new good roads had been built into Finland greatly reducing the earlier dependency on naval support for any large operation in Finland.

The Swedish plan was to first passively defend and hold on to the fortifications in the southern coast of Finland, in which Sweden had strong garrisons, while the rest of the Swedish Army retreated to the north. Then in the spring, counterattack simultaneously from north and south, when the Swedish army would have naval support and the Russian army would be spread over Finland and thus have long supply lines. The basic reason for the plan was to avoid major decisive battles.

Some advocates existed for taking a more active approach immediately, namely Lieutenant Colonel Samuel Möller (fi) who advocated for taking an immediate offensive and Gustaf Mauritz Armfelt who supported actively delaying the advancing enemies in co-operation with the garrisons on the southern coast.

In the end, instructions which the new Swedish commander in Finland, General Wilhelm Mauritz Klingspor, received from the king were an unsuccessful and open-ended mixture of ideas from these very different plans.

Russia had gathered a wealth of information from Finland using spies and other sources. The level of detail was so great that Russian maps of Finland were in many respects more accurate than their Swedish counterparts. The Russians used the services of General Georg Magnus Sprengtporten when forming their plans. Sprengtporten suggested going on to an offensive during the winter since Finland would be mostly isolated when seas were frozen. His ideas were further developed by General Jan Pieter van Suchtelen before General Friedrich Wilhelm von Buxhoeveden was appointed as the commander of the Russian army in Finland in December 1807.

The plan involved using the series of fortifications built after 1790 as staging grounds for the Russian advances into Finland. In southern Finland, armies were to isolate the fortifications and first take control of the whole of southern Finland before advancing further to the north. Forces in Savonia were to press hard against the Swedes and reach the Gulf of Bothnia towards Oulu and Vaasa