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.

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.

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 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.

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.

[7] On February 21, 1808, 24,000 Russian troops under Friedrich Wilhelm von Buxhoevden crossed the border in Ahvenkoski and took the town of Lovisa (Finnish: Loviisa).

[10] Sveaborg (Finnish: Suomenlinna) under Admiral Carl Olof Cronstedt had been well prepared for the war with a garrison of 6,000 men, over 700 cannons, and enough stores to last until the summer of 1808.

The fortress surrendered on 6 May 1808 after prolonged negotiations with the Russians as the commanding officer Carl Olof Cronstedt and his council believed that resistance was futile.

Due to various disagreements with the Swedish king, however, they never landed and sailed off to fight the French in Spain after leaving 16 battleships and 20 other ships at Sweden's disposal.

[14] In addition, Colonel Johan Bergenstråhle landed 1,100 Swedes just a few kilometers northeast of Vasa on 25 June and managed to quickly advance to the town.

To prevent the Russians from gaining strength, the Swedish coastal fleet's unit under Rear Admiral Claes Hjelmstjerna tried to engage them twice in battle.

While none of the fights ended with a decisive winner, the overall strategic victory went to Russia, who gained advantage in the Finnish archipelago by managing to link up their separate coastal units.

In the south, the Swedish battle fleet remained anchored within the Finnish archipelago, blocking some of the deeper coastal sea routes from Hangö towards Åbo.

Swedish patrol ships (consisting of armed merchant vessels) scouted and raided the coast, taking Russians prisoners to Åland.

More Royal Navy ships (including HMS Victory, Mars, Goliath, and Africa) arrived to oversee a blockade of the Russian fleet at Baltiyskiy Port which continued until the sea started to freeze.

However, owing to bad weather, only a portion of the troops that had been intended to participate in the landing actually reached the Finnish coast, and this resulted in another withdrawal on 28 September.

In April Napoleon began to devote more attention to the situation in Spain, and the British navy remained a continuous threat for troop movements between Denmark and Sweden.

With this objective in mind, Kamensky suggested a daring plan, whereby the Russian army was to cross the frozen Gulf of Bothnia at two locations: one unit was to march from Vasa towards Umeå and the other from Åbo to Åland and thence towards the vicinity of Stockholm.

Four days later, Bagration's corps of 17,000 men occupied the strategic Åland Islands, while Kulnev led a vanguard further across the frozen sea that on 19 March reached the Swedish shore within 70 km from Stockholm.

The third force, commanded by Count Shuvalov, struck against Torneå and, braving fierce frost, encircled a Swedish army, which capitulated on 25 March.

Six days later, the tsar arrived in Åbo and, on learning about the truce, not only revoked Knorring's signature but named Barclay de Tolly as the new commander-in-chief.

Total British control of the Gulf of Finland was a large obstacle to the Russian supply network and required sizable garrisons to be posted all along the Finnish coast.

[23] In August, Charles XIII, anxious to improve his position at a peace settlement, ordered General Gustav Wachtmeister to land in the north of Sweden and to attack Kamensky's rear.

Engagements at Sävar and Ratan proved inconclusive and Kamensky succeeded in neutralizing this belated counter-offensive, following up with a final victory over the Swedes at Piteå.

Wachtmeister's action was only a prelude to the peace negotiations that opened in August and resulted in the Treaty of Fredrikshamn (17 September), in which Sweden ceded the whole of Finland and all of its domains east of the Torne river (the north-eastern parts of what was then called Västerbotten, today Norrbotten) to Russia.

Sweden then joined the Continental System and closed its harbours to British ships, leading to a formal declaration of war on Great Britain.

Had the king accepted the landing of 10,000 British troops in Skåne, where the expeditionary force had been authorized to disembark, it would have enabled the Swedes to release at least 10,000 trained soldiers for the Finnish War.

[26] In memory of the 200th anniversary of the Finnish War, all Swedish 1 krona coins minted during 2009 featured a stylised depiction of the sky and the sea on the reverse side, flanked by a quote by Anton Rosell: Den underbara sagan om ett land på andra sidan havet ("The wonderful story of a land on the other side of the sea").

[citation needed] According to two 2015 studies by political scientists Jan Teorell and Bo Rothstein, Sweden's loss in the Finnish War led to reforms of the Swedish bureaucracy.