Lake Ladoga Stolbovo, the northern and western coast was ceded by Russia to Sweden. In 1721, after the Great Northern War, it was restitution to Russia by the Treaty of Nystad. Later, in 1812–1940 the lake was shared between Finland and Russia. According to the conditions of the 1920 Tartu Peace Treaty militarization of the lake was severely restricted. However, both Soviet Russia and Finland had flotillas in Ladoga (see also Finnish Ladoga Naval Detachment). After the Winter War (1939–40) according to the Moscow Peace Treaty, Ladoga, previously shared with Finland, became an internal basin of the Soviet Union. During the Continuation
Finnish reconquest of Ladoga Karelia (1941) had already reached the shore of lake Ladoga at Lahdenpohja and cut the Soviet divisions north-west of lake Ladoga from their intended withdrawal routes. Near Sortavala the attacking Finnish forces of 2nd, 7th and 19th division were reorganized into the I Army Corps and the town fell to the Finnish forces on August 15. The defending Soviet forces of the 168th Rifle Division withdrew along the coast but were encircled. The Soviets managed to evacuate most of the manpower on barges over the lake Ladoga. Finns captured large amounts of war material that the Soviets had not been able to