The name of this Italian naval cable-layer was GIASONE, not CHISONE, and was not the vessel attacked by the Free-French submarine CASABLANCA.

The GIASONE was taken by the Germans at Genoa on the capitulation of Italy. K R Haigh's "Cableships and Submarine Cables" (London 1968) says that she was found at Marseille and taken over by the French. (She was only built in 1941 as a replacement for the previous GIASONE, which was sunk by a mine on 4 Oct 1940 between Trapani and Pantellaria)

Bertrand Daubigny also notes CHISONE as an Italian freighter - see
[perso.wanadoo.fr]