Vesikko at war 1939-44

After the war Finland was still independent but internationally very isolated. During the short peacetime the submarine flotilla could exercise very little because of a lack of fuel. In 1940 Vesikko got a Danish 20 mm anti-aircraft gun Madsen on her fore deck.

The first summer of the Continuation War (Russian - Finnish war 1941-44) was filled with busy action for the submarines. Vesikko went patrolling to the eastern part of the Gulf of Finland. On one of those missions, on 3 July 1941 near Suursaari (Gogland) island, Senior Lieutenant Olavi Aittola, the commanding officer of Vesikko, noticed an enemy freighter.

After torpedoing, the Russians made a depth charge attack. The crew had to stay in silence for hours on end before the submarine could leave the area and return safely to her base. 

In 1942 the most important mission of the submarine flotilla was exceptional: searching and destroying enemy submarines which were harrassing the Finnish commercial ships on their way to Sweden. Vesikko took part in the action both on the Aland Sea and on the Gulf of Finland. 

Next year was very silent. The submarine net and mines laid down by the Finnish Navy and the Kriegsmarine together tied the Soviet Baltic Fleet to the end of the Finnish Gulf.

In 1944 the silence was interrupted. The Russians took over Narva in Estonia and started a massive offensive in the Carelian Isthmus. The Finnish submarines were sent to the East to support the defence and cover transportation. Vesikko did not meet suitable targets.