Bonjour René,

I suppose you are referring to the 18.4.1940 attack when NAUTILUS reported missed by 2 torpedoes in Quadrat 4126. She was then escorting a southbound convoy along with T.190, M.75, PELIKAN and ELBE.
STERLET may have been the submarine involved but she did not return from patrol so we cannot be absolutely sure. The attack may also have been a bogus one as there a few instances when such attack were reported and no submarine was in the vicinity.
NAUTILUS was the same vessel which took part in Group 7 (Nyborg and Korsör). She was part the SVK flotilla(Sperrversuchskommando) and had been acting as leader when escorting the III/Staffel/2 convoy to Oslo (BELGRANO, FRIEDRICH BREHME and KÖLN) arriving on 15.4.40. It was on the return trip (escorting NEIDENFELS, MOLTEKEFELS and HANAU) that the presumed attack occurred.

Best regards,

Platon