On 21 October 1940, after a first attempt interrupted due to the absence of enemy units in the port of Gibraltar, the submarine Scirè, under the command of Lieutenant Commander Borghese, takes to sea again for the BG2 operation following the report of the presence of the battleship Barham, a cruiser and some other units. The operators of the three Slow running torpedoes they were the lieutenant Birindelli and second chief diver Paccagnini, the captain gn Tesei and sergeant diver Pedretti and the second lieutenant Durand de la Penne and second chief diver Bianchi.
At 02.19 on 30 October the attackers departed from Scirè on board their SLCs, while the vessel submerged away: Birindelli was supposed to attack the Barham, Tesei the cruiser, while De la Penne, having carried out an initial reconnaissance in search of other possible targets, was also supposed to attack the ship from battle.
The Birindelli-Paccagnini couple immediately have to face many difficulties with the governability of the vehicle and, after an hour of effort, they reach obstructions: Birindelli, alone, due to the exhaustion of Paccagnini's breathing apparatus, reaches 70 m from the Barham first that the vehicle becomes permanently immobilized on the bottom. Once the explosive charge has been triggered, the officer then reaches the pier trying to mingle with the Spanish workers working in the port. Captured, like Paccagnini, he manages to resist interrogations while maintaining the secret of the mission accomplished.
The De la Penne-Bianchi couple carries out the planned reconnaissance but, due to damage, the vessel sinks without being able, despite their extreme efforts, to bring it closer to a target, but they manage to avoid capture thanks to the help of some fishermen and reach subsequently Spanish territory.
Tesei and Pedretti also suffered a series of failures with their breathing apparatus and the SLC, and to avoid interference in the actions of the other two vehicles, they decided to give up and take refuge in Spain. Despite the apparent failure of the mission, due to the material not yet ready, the BG2 operation marked a notable progress compared to the previous ones, as the insidious vehicles had arrived at the expected point and one, overcoming the enemy defenses and preparations, he had entered the equipped base. It was therefore fundamental for the planning of the subsequent mission to Alexandria on the night between 18 and 19 December 1941, one of the largest and most daring undertakings in the history of naval conflict in the Mediterranean.
A prophecy that came true in a letter from Lieutenant Gino Birindelli who, after his long imprisonment, wrote in code: "tell my brother to repeat his degree exams; by trying and trying again he must succeed; by preparing well, he will not find insurmountable obstacles".
