northern islands in the 16th and 17th century. According to legend, the notorious pirates known as the Victual Brothers, who terrorized the Baltic Sea region in the Middle Ages, would have lit stray fires in the Archipelago Sea, which would have lured other ships to shore, looted the booty and possibly killed the ship's crew. This is apparently just a later story tradition. According to the same tradition, the pirates were also joined by young adventurous men from coastal villages who did not see a future for themselves in their home region. In 1808 the War of Finland broke out between Sweden and Russia. In April Russian troops occupied the archipelago, including Åland. Soon after the local residents, enraged by the confiscation of ships, rebelled. Aided by troops from Sweden the archipelago was cleared from Russian troops in May. The Swedish troops then used the islands as a staging area for the recapture of continental Finland. The archipelago remained in Swedish control until the end of the war, but in the subsequent Treaty of Fredrikshamn in 1809 Sweden was forced to cede the area along with rest of Finland. The Archipelago Sea became part of the autonomous Grand Duchy of Finland under the Russian Empire. Grand Duchy of Finland During the Crimean war an Anglo-French force attacked and destroyed the Bomarsund castle. In the Åland convention of 1856 the Åland side of the archipelago was demilitarised. The Russians moved troops back into the area in 1916, and for the next 5 years there was either Russian or Finnish military presence in Åland. Independent Finland Finland gained its independence from Russia in 1917. Shortly after, the Swedish speaking inhabitants of Åland, in the western part of the Archipelago, appealed to Sweden to annex the islands. The request received mixed support in Sweden, but led to the Åland crisis. The League of Nations was called in to resolve the situation, and in 1921 the League granted the sovereignty of the entire archipelago to Finland, despite the objections of the majority of Ålanders. However, Åland was given a wide autonomy, and its demilitarised status was reaffirmed. In 1939 the Soviet Union attacked Finland in the Winter War. At the end of the war in 1940 Finland was forced to rent Hanko at the eastern extreme of the Archipelago Sea to Soviet Union as a military base. In 1941 the Continuation War broke out.