Finnish minelayer Riilahti Riilahti was a Ruotsinsalmi class minelayer of the Finnish Navy . " Riilahti " was commissioned in 1940 and sunk in 1943 . The vessel was named after the battle of Riilahti , which was fought between Sweden and Russia in 1714 . New minelayers for the navy . Funding for two new minelayers had been secured as early as in 1937 , but instead the money was used to refurbish the garrison at Mäkiluoto . " Riilahti " was launched on December 14 , 1940 , three weeks after her sister ship " Ruotsinsalmi " . The ship had an extensively modified propulsion system and hull , compared to her sister vessel , and it took some time before the crew had figured out all the characteristics of the vessel . Originally , the vessels were intended as escort minesweepers for the Finnish navy ' s coastal defence ships " Ilmarinen " and " Väinämöinen " , and they were therefore designed with a draft of only 1 . 5 m . " Riilahti " was armed with one 75 mm gun , one Bofors 40 mm gun s and two Madsen 20 mm anti - aircraft cannon s . The vessel had three mine dropping rails , and could carry about 100 mines . The ship could also hunt submarines , and was equipped with sonar , depth charge throwers and rails . The vessel was also strong enough to be ale to tow minesweeping equipment . She was equipped with smoke generator s so she could protect itself , and other near - by vessels from the enemy . " Riilahti " was commanded by " kapteeniluutnantti " Osmo Kivilinna during her entire career . Riilahti during the Continuation War . " Riilahti " and " Ruotsinsalmi " began mining the Gulf of Finland on June 26 , 1941 , immediately after the outbreak of the Continuation War . " Riilahti " launched almost 1 , 000 sea mine s during 1941 , most of them in the Juminda minefield . In 1941 , " Riilahti " managed to seize control of a Soviet barge and participated in minesweeping operations south of the Hanko Peninsula . In the summer of 1942 , " Riilahti " laid numerous mines near Hogland . " Riilahti " was sent as reinforcement to the island of Someri on 8 July 1942 , when the Russians tried to land and take the island . She was involved in artillery duels with ships from the Soviet Navy , gave fire support to the Finnish defenders on the island and fended of several air attacks . The vessel counted 56 aircraft attacking her , but she survived , thanks to the gallantry of her crew . The island was held by the Finnish defenders . The Marshal of Finland , Mannerheim awarded the Mannerheim Cross to Osmo Kivilinna on 8 March 1943 , citing the war record of the ship , whose characteristics still were not all known . The ship had also previously sunk the Soviet submarine Shch - 406 together with some German patrol vessels on 26 May 1943 . The last battle . On August 22 , 1943 at 5 . 30 am , " Riilahti " set out from Loviisa on an anti - submarine mission west of Hogland . The patrol vessel VMV 1 followed her on the journey . At 2 pm on August 23 an outlook spotted two Soviet motor torpedo boat s and sounded the alarm . The officer on duty had previously ordered the engines to be stopped so that the sonar operators easier could listen for submarine sounds . While the vessel tried to start her engines and reach steering power , the Soviet motor torpedo boat TK 94 fired a torpedo , which struck " Riilahti " amidships and broke her in two . " Riilahti " sunk in two minutes , taking with her 23 of her crew . VMV 1 saved eleven men from the water , one being the commander of the ship , and Mannerheim knight Osmo Kivilinna . He later died from his wounds on the operating table . This was one of the most significant single losses during the war years ; Kivinlinna was a very well - liked officer , and it was widely believed that he could become the first full Admiral of the Finnish Navy . The wreck of " Riilahti " lies five nautical miles from the island of Tiiskeri at a depth of 70 m . The loss of " Riilahti " left the Finnish Navy with a gap in their mine warfare capabilities . This was addressed with the launching of the " Keihässalmi " in 1957 . The third engine , which had been ordered , but not yet fitted on the " Riilahti " was instead fitted onto the sister vessel " Ruotsinsalmi " . " Riilahti " laid 1 , 733 sea mines and 599 obstacles during her career .