After the conquest of Finland by Russian armies in 1808, Sweden had to cede Finland to Russia in 1809 (the Treaty of Fredrikshamn). The Diet of Porvoo in 1809 was a landmark in the History of Finland. The Tsar Alexander I confirmed the new Finnish constitution (which was essentially the Swedish constitution from 1772), and made Finland an autonomous Grand Duchy. In 1923, six years after Finland's independence, the former Diocese of Vyborg, which operated in Porvoo, was replaced by a current Swedish-speaking diocese of the Evangelical Lutheran Church of Finland, the Diocese of Porvoo.