[1] Berillo was built by CRDA at their shipyard in Monfalcone, laid down on 14 September 1935, launched on 14 June 1936 and completed on 5 August 1936.

[4] During 1936 Berillo underwent an intensive endurance training cruise in the central Mediterranean, sailing between Tobruk, Benghazi, Marsa el Hilal, Bardia, Leros and Naples.

On 1 January Berillo left Naples under command of Captain Vittorio Prato for the first mission to be carried out off Cartagena.

At the time of Italy's entrance into World War II, Berillo, together with Gemma and Onice, was assigned the 13th Squadron (I Submarine group) based at La Spezia, operating from Augusta.

[4] On 13 July 1940 she was deployed along with the largest submarines Morosini, Nani and Comandante Faà di Bruno to an area east of Gibraltar.

On 18 September 1940 Berillo was ordered to patrol off Sidi Barrani and Marsa Matruh in support of the Italian offensive in Egypt.

At 21:30 on 29 September, Berillo received a radio message informing her about a scattered enemy battle group that was detected nearby consisting of a battleship, an aircraft carrier, five cruisers and nineteen destroyers.

As the distance shortened to 600 meters (660 yd), Ferretti ordered two more torpedoes fired but they missed their intended target again, with one of them going just under one of the destroyers without exploding.

[7] He then ordered hard to starboard to launch from the stern tubes, but at this point, the British ships simultaneously illuminated Berillo with four searchlights, and at the same time fired from their guns.

[6] Berillo went to about 90 meters (300 ft) in 32 seconds, and the depth charge attacks commenced, knocking out her electricals, intercom system, pressure gauges and diving planes.

[4][6] The next set of attacks damaged and knocked out the engines, propellers, started a fire in the aft compartment and opened water leaks in the hull.

[8] The captain ordered to blow all air to try to save the submarine and her crew, and Berillo started slowly rising and eventually at 05:30 on 2 October, she flew out of the water with a list of 45°.

One of the shots knocked out the deck gun, and the other one penetrated the conning tower, killing two crewmen who were trying to open the hatch.

As everyone left the submarine, she sank in the approximate position 33°09′N 26°24′E / 33.150°N 26.400°E / 33.150; 26.400 about 120 nautical miles (220 km) north of Sidi Barrani.