There were countless forcing operations in English ports undertaken by the men of the X MAS Flotilla during the Second World War, to sink or damage enemy ships. As part of this action strategy, on 7 May 1943, under the command of Lieutenant Captain Ernesto Notari, the operation started BG 6. As objectives of the mission, Notari chose the British merchant ships, loaded with goods, at anchor in the bay of Algeciras, to damage the supply capacity of the Allies. Considerable damage had to be inflicted on enemy vessels but it was equally necessary to distract the British navy from turning its attention to theOlterra, the ship (which was stationed in the Spanish port of Algeciras), used as a base for the X Flotilla MAS for incursions into the port of Gibraltar.
The Royal Navy had, at the same time, established a special team of divers, theUnderwater Working Party (UWWP), under the command of Lionel Crabb, with the difficult task of inspecting the hulls of the boats, looking for explosive devices placed by the Italians and removing them. Crabb then initiated the operation Tadpole, a real action of prevention and contrast against the attacks of the X Flotiglia MAS in the port of Gibraltar and in its vicinity, whose existence Notari's men were unaware of.
At 22.35 pm on 7 May, three squads of SLC (Slow Running Torpedoes) emerged from the underwater port of the Olterra towards the bay of Algeciras. BG 6 had begun.
For the crews, the approach march was extremely difficult, due to the strong currents. Moreover, with the operation Tadpole, the British had increased the patrolling of the lookouts, from which, every six minutes, depth bombs were dropped close to the merchant ships. This last difficulty did not deter the three crews from continuing the mission.
The second lieutenant Vittorio Cella and the diver sub-chief Eusebio Montalenti carried out the operation first. Despite the laceration of Montalenti's suit and leg cramps that prevented him from moving, they managed to position the SLC's explosive head at the roll wings of a steamer. The situation was different for Notari's team with the second diver chief Ario Lazzari who had to make an enormous physical effort to keep the SLC stable due to the sea currents. The initial plan to place the charges on two vessels was shelved and both were applied to one vessel. During the mission, Notari was also able to implement a misdirection plan, scattering some equipment on the beach north of Gibraltar, so as not to make the British understand where the exact place from which the three teams had left was.
The team of lieutenant of the naval genius Camillo Tadini and of the diver sub-chief Salvatore Mattera took longer than the other two to conclude the operation due to the presence of some Spanish fishing boats. They returned last, at 4.15 am, after placing the explosive head of the SLC at the bottom of a boat.
At 6.15 am on May 8, the bay of Algeciras was awakened by the deafening noise of the first detonation. Shortly thereafter the other charges positioned on the boats exploded in succession. The Pat Harrison, Mashud and Camerata ships, all cargo steamers, suffered extensive damage.
Thus Emilio Bianchi commented on the success of the mission: "three ships for about 20.000 total tons disappeared in the waters of Gibraltar". The British admitted the gravity of the losses and Crabb, incredulous in front of the Italians' ability to elude the defensive system he had designed himself, had to increase the security measures by equipping the Allied ships, present in the Bay of Algeciras, with a barbed wire fence above the roll fins.
In a few hours, the operation BG 6 demonstrated the ineffectiveness and failure of the strategies adopted by the Royal Navy to stem the X MAS Flotilla. The incessant explosions of depth bombs and the frequent patrols of the British lookouts did not prevent the crews of the three SLCs from completing the mission.