December 1942, Operation N.A. 1
The submarine Ambra was supposed to bring a mixed unit near the Algerian port: three SLCs with their crews (6 men) and 10 “Gamma men” (divers saboteurs) of the X MAS (the “Gammas” were composed of elements of both the Navy and the Army, 5 and 5; their commander was the lieutenant of the Naval Arms Corps Agostino Morello); the submarine would release “Gamma” and SLC while resting on the bottom of the sea, while two men from the X MAS would remain on the surface, acting as lookouts.
The submarine Ambra
On December 4th, in the early afternoon, the submarine left La Spezia and three days later arrived off the Algerian coast; however, due to adverse weather and sea conditions, he had to wait until December 11th before he could approach Algiers to begin the final phase of the operation. Navigating submerged to elude the strong vigilance, and with the echo sounder broken, the submarine hit the seabed abruptly at about ninety meters. The boat kept dragging on the sandy bottom until it reached a depth of about 18 meters and then came to a rest. However, when the two lookouts were sent to the surface, it turned out that the coast was not visible, nor were any ships to be seen.
A ‘SLC’ (slow moving torpedo, also knows as ‘pig’ or ‘chariot’
Moving again and very close to the seabed, stopping from time to time to send lookouts to the surface, the submarine finally found itself inside the bay with 6 merchant ships moored all around. Since they were already behind schedule, the raiders were sent out (first the “Gamma”, between 10.30 and 11 PM, followed by the SLC between 11 PM and 11.20 PM. However, the crews did not act with coordination: only one of the SLCs and five “Gammas” managed to carry out the attack, while the others hurried to try to return to the submarine and one surrendered to the local authorities, thus triggering the alarm. Despite the risk the Ambra remained on the bottom until 2.54 AM, before having to leave without anyone having returned; the raiders had all fallen prisoners.
Commander Mario Arillo
During the departure there was also a collision with a wreck, fortunately without consequences; It was not until 19:45 on December 12th – after being submerged for 36 hours – that the Ambra was able to return to the surface, recharge the batteries and refresh the air supply. At noon on the 15th, the submarine docked at La Spezia. Although less than half of the raiders managed to plant explosive charges, the steamers Ocean Vanquisher (7174 GRT) and Berto (1493 GRT) were sunk, and two other large merchant ships, the Empire Centaur (7041 GRT) and the Armattan (4558 GRT) suffered serious damage. Commander Mario Arillo received the Gold Medal for Military Valor; twelve of the raiders were decorated with the Silver Medal for Military Valor and another with the War Cross for Military Valor.