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 Ladoga Naval Detachment losses. In the spring 1942 Finnish commander made recommendations to German leadership past Finnish HQs leading to the formation of Naval Detachment K, which included the Finnish motor torpedo boat "Sisu", to the lake. They were also joined in summer 1942 by a German unit, the Einsatzstab Fähre Ost (EFO), of armed Siebel ferries. Operations of the Naval Detachment K or EFO had very limited success. When Germany decided to withdraw its naval assets from Ladoga in late 1942, the Finns bought two of the Siebel ferries, "T-2" and "T-17". Later, when the Soviets' 1944 offensive against the Finns began,