After Tarantini was sunk, Bagnolini and Giuliani were selected for conversion to "transport submarines" in order to exchange rare or irreplaceable trade goods with Japan.

[1] Two weeks after the Italian declaration of war, Liuzzi was sunk by Royal Navy destroyers south of Crete on 27 June 1940.

Bagnolini was at sea when Italy declared war, and torpedoed the cruiser HMS Calypso south of Crete on 12 June 1940.

After an unsuccessful BETASOM patrol in November, Giuliani sailed on 16 March 1941 to serve as a training submarine at Gdynia to instruct Italian officers in attack techniques and methodologies employed by the Germans.

Giuliani remained in the Spanish port of Santander, Cantabria until 8 November 1942 repairing damage inflicted by Short Sunderlands on 1 September and No.

[5][6] After return to France and conversion to a transport submarine, Giuliani sailed on 16 May 1943 with 130 tonnes of mercury and reached Singapore on 1 August 1943.

Tarantini began its first BETASOM patrol on 11 November and was torpedoed by HMS Thunderbolt in the Gironde estuary while returning to base on 15 December 1940.