In 1906, a unit of 750 Russian soldiers was sent to Prästö, although the Åland Islands had been demilitarized since the 1856 Treaty of Paris. The islands were used for smuggling weapons and illegal publications to the Socialist revolutionaries in Russia. The smuggling route ran from Stockholm to Åland and then via Southern Finland to Saint Petersburg. In order to chase the smugglers, the Russians built a telegraph line from Åland to the Finnish mainland. One of the telegraph stations was built in Prästö. During the 1918 Finnish Civil War Invasion of Åland, the Prästö telegraph station was occupied by Whites who had landed the island from Finland. Today the 1913 built telegraph station works as museum which is open during the tourist season.