3 Sep, 1942
S-13 sailed from Lavansaari Island for a war patrol.

11 Sep, 1942
S-13 torpedoes and sinks the Finnish merchant Hera (1379 GRT) in the Gulf of Bothnia in position 60º56'N, 19º06'E. (see map)

12 Sep, 1942
S-13 torpedoes and sinks the Finnish merchant Jussi H. (2325 GRT) in the Södra Kvarken in position 60º21'N, 19º00'E. (see map)

17 Sep, 1942
While continueing her patrol in the Gulf of Bothnia S-13 fires two torpedoes against ' what is identified as ' a merchant of 3000 tons. Both torpedoes missed their target.

18 Sep, 1942
S-13 sinks the Dutch merchant Anna W. (290 GRT) with gunfire in the Gulf of Bothnia about 2 nautical miles east of Kaskinen, Finland in position 62º23'N, 21º10'E. (see map)

15 Oct, 1942
While returning to base S-13 is attacked off Vaidlo by the Finish submarine chasers VMV-13 and VMV-15. The submarine is able to escape and returned to base safely.

9 Oct, 1944
S-13 fires four torpedoes against ' what is identified as ' a merchant of 5000 tons. All torpedoes missed their target. The target, that was the German fishing vessel Siegfried (563 GRT) was then engaged and damaged with gunfire north of Danzig Bay in position 55º08'N, 18º42'E. The damaged German ship was later towed to Danzig. (see map)

30 Jan, 1945
At Stolpe Bank off the Polish coast in position 55º08'N, 17º41'E, S-13 torpedoes and sinks the German liner Wilhelm Gustloff (25484 GRT) carrying at least 6000 to 7000 people and most likely even more, only about 900 people survived the sinking. Wilhelm Gustloff was taking officials, soldiers, refugees, women and children plus some 300 U-boat personnel from Danzig, Poland to Kiel. (see map)

10 Feb, 1945
S-13 torpedoes and sinks the German General Steuben (14660 GRT) north of the Stolpe Bank in position 55º18'N, 16º38'E. Over 3800 wounded and refugees lost their lives. (see map)