Mario Arillo was born in La Spezia on the 25 March 1912 and soon showed a great passion for the sea and the desire of following a career in the Royal Navy. La Spezia had one of the biggest Italian naval bases and had a good tradition in the ship building industry.
In 1927 he was admitted to the Livorno Naval academy and graduated as Guardiamarina five years later. He was assigned to the destroyer Trieste, and then the torpedo boat Stocco, and finally on the explorer Giovanni da Verrazzano between September 1933 and October 1934.
He started his secondary education at the Livorno Academy in 1934 and 1935, and then became second communication officer on the torpedo boat Dardo, and second officer on the old submarine H2 in La Spezia.
Between 1936 and 1938 he was assigned to the destroyers Trento, Trieste, and Duca degli Abruzzi, where for a short period was the assistant to the Admiral Commander of the 3° Naval division. He returned to the Livorno academy in September 1940 to study at the submarine school of Pola. He spent the period at the command school on the submarine “Ettore Fieramosca”, built as a single class: 82 meters long, 8,04 wide with an immersion capacity of 5,3. The submerged range was 90 miles at 3 knots of speed, reaching a maximum speed on the surface of 18 knots and submerged at 9 knots, total weight 1,550-1,900 tons. The submarine was armed with a 120/45.4 cannon, 4 13.2 mm machine guns and 8 533mm torpedo launchers.
On the 19th of January 1941, Mario Arillo was assigned to the Ambra with the rank of Lieutenant Commander. This submarine destined for Mediterranean War was smaller and more agile. It weighted 695-855 tons, dimensions 60* 6.45*4.7m, speed 14-7.5 knots autonomy 74 miles and four knots submerged. It was armed with a 100/47 cannon, 2 13.2 machine guns and 6 533m torpedo launchers. The Ambra was designed to ambush the British transports in the central and eastern Mediterranean, and at a certain point to transport assault military equipment and machines.
On May 31th 1941, Arillo had his first opportunity. A British naval column composed of the destroyer HMS Bonaventure (Cap. H.J.Egerton, 5,450 tons), and destroyers HMS Hereward and Stuart traveling from Alexandria, Egypt was intercepted by Arillo while sailing South of Crete transporting Commonwealth troops to defend the Island. (in a few weeks there was bloody and strong combat between New Zealand and Greek troops and the German paratroopers, an operation that the German Wehrmacht coined as Operation Merkur. In spite of the heavy casualties on the German side, the British troops were forced to retreat).
At 2:44 of that day, Mario Arillo fired 3 torpedoes. One slightly missed the Hereward. The others hit the Bonaventura which sank a few hours later. The Stuart saved 310 men, but 138 (others say 170) lost their lives. The strong defense of the Hereward by launching 7 depth charges did not change the outcome. After this event, Mario Arillo earned a Medaglia d’argento al valor militare.
On April 29th, 1942 Operation G.A.4 departed from La Spezia and the port of Alexandria was the objective. Although the raiders and Siluro a Lenta Corsa (SLC) involved didn’t damage the port or ships, Arillo was honored with a second Medaglia d’argento al valor militare for his brilliant operational approach and the rescue of the survivors near the coast while under enemy fire.
After the spring and summer successes for the German-Italians troops, October began to bring some disappointments. The Allied troops invaded Morocco and Algeria which changed the dynamics of the North African front. The Axis troops were trapped by stronger forces east and west from Libya and Tunisia.
One of the diversion actions tried in this desperate situation was the operation N.A.1. The goal of the operation was to attack the Algerian bases with 6 SLC and 10 frogmen. On the night of the 11-12 December, the Ambra bravely left the raiders right in the center of the port. The Norwegian steam ship Berto (1,493 tons) was sunk. The English steamships Empire Centaur, 7,000 tons, Harmattan, 4,600 tons and Ocean Vanquisher (7,200 tons), were seriously damaged. The Ambra, and his captain, deserved the golden medal to the military value, but unfortunately returned to La Spezia without its 16 frogmen, who were captured by the enemy.
During the spring of 1943, several submarines were destined to transport materials to the Japanese. The Italian submarines involved were: Archimede from the “Brin” class, Barbarigo and the Cappellini of the “Marcello” class, Finzi and Tazzoli from the “Calvi” class, Bagnolini and Giuliani from the “Liuzzi” class, and finally the Torelli and Da Vinci from the “Marconi” class. In exchange the Kriegsmarine supplied 9 U-boots of the VIIC class, that were reclassified by the Royal Navy as S class with progressive numbers 1 to 9. They were dependable ships of 770-1,070 tons, with 66*6,2*4,7m, autonomy 80 miles at 4 knots, speed 17,6-7,6 knots, armed with 6 torpedoes launchers with electronic mechanic control board and 2 machine guns of 20/70. With an excellent submerged speed (25 seconds until 150-180 m. deep). The ship crews were moved to Danzig were they started training in the new units. After the 8 September armistice the submarines were immediately recovered by the Germans.
Arillo decided to become a member of RSI, acting as mission leader of the Decima Mas. In particular he was involved in combat actions in Anzio on 23 January, and then from bases in Liguria in actions in southern France between August 1944 and April 1945. He participated and organized the Sergio Denti’s action, that sank the Trombe on the last days of the war. He transferred to a naval reserve in August 1945 as Capitano di Fregata.
Besides the 2 Medaglia d’argento al valor militare and 1 Medaglia d’oro al valor militare, Arillo earned one Medaglia di bronzo al valor militare and the German Iron Cross Second Class. He died in Venice 26 September 2000.
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