The Finnish Navy was informed that the 8,800 ton Soviet icebreaker Yermak would be arriving in the Baltic Sea from the Atlantic.

However, the submarine ran aground before reaching open sea and had to be pulled loose by tugs before it was able to start its voyage.

[5] The Italian torpedoes (Finnish designation "T/40") proved to be unreliable in service despite functioning during test range firings.

For this reason a report that the Finns received from the besieged Hanko that a Soviet freighter had arrived there with two Finnish torpedoes sticking out from its hull became more believable.

The submarine attacked on the surface but the poor quality of the night sight and the activity of the escort prevented torpedoes from being fired with any accuracy.

A mere 15 minutes later the submarine sighted another Soviet convoy, this time headed due West, but had no loaded tubes and was unable to engage it.

A second torpedo also missed, but the deck guns managed to damage the Soviet submarine which by then had started an emergency dive.