5 (17) September, 1809 in the city Fredrikshamn (now Hamina, Finland) Sweden and Russia signed a peace treaty which ended the Russian-Swedish war of 1808-1809. Its main outcome was that Finland became part of Russia as an autonomous principality.
Two years earlier, on 25 June (July 7), 1807 in the town of Tilsit (now Sovetsk, Kaliningrad region) at the meeting between Emperor Napoleon Bonaparte and Alexander I, was signed the Treaty of Tilsit, which actually predetermined rejection of Finland from Sweden, which had been in a state of war with France, and its annexation to Russia.
In February 1808 the Russian troops under the command of Count Fedor Fedorovich Buxhoeveden crossed the Finnish border and launched an offensive against the capital of the principality, the city of Åbo (now Turku), and took it on 10th (22) of March.
Seeing the success of Russian troops, Alexander I decided to annex Finland to Russia. On 16th (28) of March a declaration was published: "His Majesty proclaims to all the European powers that now the part of Finland, which hitherto was known as the Swedish one and which the Russian troops occupied having withstood various battles, is recognized a territory conquered by Russian arms, and annexed for good to the Russian Empire".
March 20 (April 1), 1808 a manifesto to the Russian population followed, which read: "The country conquered by our arms, we annex now and for all to the Russian Empire, and as a result we ordered the inhabitants to swear their allegiance to the Russian throne”. Manifesto declared the annexation of Finland to Russia as a Grand Duchy. Russian government was obliged to retain its former laws and the Seim.
During the Russian-Swedish war of 1808-1809 Russia managed to fully occupy Finland, and defeat Swedish troops.
5 (17) September 1809 between the two countries was signed the Treaty of Fredrikshamn.
The document was drawn up in duplicate (both French), and contained 21 articles, the preamble and the conclusion. From the Russian part the treaty was signed by Minister of Foreign Affairs, Count Nikolai Petrovich Rumyantsev and the Russian envoy in Stockholm David Maksimovich Alopeus. From Sweden: General of Infantry, a former Swedish ambassador in St. Petersburg, Baron Kurt Ludwig Bogislav Christoph Stedingk and Col. Anders Fredrik Sheldebrandt.
Treaty was to enter into force upon the exchange of instruments of ratification, which took place 1 (13) October, 1809 in St. Petersburg.
According to the Treaty of Fredrikshamn the entire Finland (including Aland Islands) went over to Russia. The treaty obliged Sweden to make peace and become an ally of Napoleon. Finland was declared the Grand Duchy of the Russian Empire and it was bestowed with an extensive autonomy. The Finnish autonomy, coming after the signing of a peace treaty, promoted the growth of economy and culture. Nevertheless, being the Grand Duchy, Finland retained the Lutheran faith and Swedish legislation.
Treaty of Fredrikshamn had been in force regarding Finland until 1920, when under to the Tartu Peace Treaty concluded between the RSFSR and Finland, the state independence of the latter was recognized.
Lit.: Мирный трактат, заключённый между Россией и Швецией. 5 (17) сентября 1809 г. // Шиловский П. Акты, относящиеся к политическому положению Финляндии. СПб., 1903. С.127-129; Похлёбкин В. В. Отношения между Шведским государством (Свитиод, Свеарике, Свейская земля, Свицкое королевство, Шведская корона, Швеция) и Русским государством (Новгородской республикой, Московским великим княжеством. Московским царством, Российской империей) в ХIII-ХIХ вв. (1142-1874 гг.) // Внешняя политика Руси, России и СССР за 1000 лет в именах, датах, фактах. М., 1995 Рисак Н. Хроника присоединения Финляндии // Спектр. 2009. Февраль. № 2 (112).
From the Presidential library materials:
Дело о праздновании 5 сентября 1909 г. столетней годовщины заключения Фридрихсгамского мирного договора. ноябрь 1908 г. - 25 ноября 1909 г. / Совет министров. (Совет министров.. Инвентарная опись № 18. Совет министров. Канцелярия по делам Финляндии. 1899-1917 год.);