The Åland Islands were part of the territory ceded to Russia by Sweden under the Treaty of Fredrikshamn in September 1809. As a result, along with all other parts of Finland, they became part of the semi-autonomous Grand Duchy of Finland.
During this process, Sweden was unable to secure a provision that the islands not be fortified. The issue was important not only for Sweden but also for the United Kingdom, which was concerned that a military presence on the islands could threaten Britain's military and commercial interests.
In 1832, Russia started to fortify the islands with the great fortress of Bomarsund. This was captured and destroyed by a combined British and French force of warships and marines in 1854 as part of the campaign in the Baltic during the Crimean War. In the 1856 Treaty of Paris, the entire Åland Islands were demilitarized.
During the Finnish Civil War, in 1918, Swedish troops intervened as a peacekeeping force between the Russian troops stationed on the islands and "White" and "Red" Finnish troops that came from Finland over the frozen sea. Historians, however, point out that Sweden may have in reality planned to occupy the islands. Within weeks, the Swedish troops gave way to German troops that occupied Åland by request of the "White" (conservative) Finnish Senate.
After 1917, the residents of the islands worked towards having them ceded to Sweden. In 1919 a petition for secession from Finland and integration with Sweden was signed by 96.4% of the voters on the islands, with over 95% in favour, although serious questions were later raised regarding this extraordinarily high figure. Swedish nationalist sentiments had grown strong particularly as a result of the following issues: anti-Swedish tendencies in Finland, Finnish nationalism fuelled by Finland's struggle to retain its autonomy, and the Finnish resistance against Russification. In addition, the conflict between the Swedish-speaking minority and the
