Italian submarine Pietro Calvi

Pietro Calvi was the lead ship of its class of two submarines built for the Regia Marina (Royal Italian Navy) during the 1930s. Completed in 1936, she played a minor role in the Spanish Civil War of 1936–1939 supporting the Spanish Nationalists. The submarine made multiple patrols in the Atlantic Ocean during the Second World War, sinking seven Allied ships. Pietro Calvi was rammed and sunk by a British convoy escort in July 1942.

Design and description
The Calvi class was an improved and enlarged version of the preceding Balilla-class submarine submarine cruisers. They displaced 1525 LT surfaced and 2028 LT submerged. The submarines were 84.3 m long, had a beam of 7.7 m and a draft of 5.2 m. They had an operational diving depth of 90 m. Their crew numbered 77 officers and enlisted men.

For surface running, the boats were powered by two 2200 bhp diesel engines, each driving one propeller shaft. When submerged each propeller was driven by a 900 hp electric motor. They could reach 16.8 kn on the surface and 7.4 kn underwater. On the surface, the Calvi class had a range of 11400 nmi at 8 kn; submerged, they had a range of 120 nmi at 3 kn.

The boats were armed with eight 53.3 cm torpedo tubes, four each in the bow and in the stern for which they carried a total of 16 torpedoes. They were also armed with a pair of 120 mm deck guns, one each fore and aft of the conning tower, for combat on the surface. Their anti-aircraft armament consisted of two twin-gun mounts for 13.2 mm machine guns.

Construction and career
Pietro Calvi (pennant number CV) was built by Odero-Terni-Orlando at their Muggiano, La Spezia, shipyard. Laid down in 1932, the submarine was launched on 31 March 1935 and completed in 1936.

During the Spanish Civil War, she unsuccessfully fired a pair of torpedoes each at the mail steamer SS Villa de Madrid and the 3946 GRT mail steamer SS Ciudad de Barcelona during a patrol on 1–17 January 1937. During the night of 12/13 January she bombarded the port of Valencia.

The first patrol during the Second World War was from Liguria to the Atlantic Ocean, and lasted from 3 July to 6 August 1940. After overhaul at La Spezia, Pietro Calvi sailed on 6 October for a second Atlantic patrol reaching Bordeaux, France, on 23 October. The submarine suffered storm damage during its third patrol off the British Isles from 3 to 31 December. The fourth patrol was between the Canary Islands and the Azores from 31 March to 13 May 1941. She sailed on 1 August for a fifth patrol off the Canary Islands. During the sixth patrol from 7 to 29 December Pietro Calvi, ITALIAN SUBMARINE Giuseppe Finzi and ITALIAN SUBMARINE Enrico Tazzoli rescued sailors of the sunken German commerce raider GERMAN AUXILIARY CRUISER Atlantis. The seventh patrol was off Brazil from 7 March to 29 April 1942. The submarine sailed on 2 July for its eighth patrol. Pietro Calvi was rammed and sunk on 14 July by the British sloop HMS Lulworth which was able to briefly board the submarine before she sank. British ships rescued 35 of her crew of 78 men; among those killed was the commanding officer, Commander Primo Longobardo.