Italian submarine Diaspro was a built for the Royal Italian Navy (Regia Marina) during the 1930s. She was named after a gemstone Jasper.
Design and description
The Perla-class submarines were essentially repeats of the preceding . The modifications that were made compared to the boats of the previous series were mostly of upgrade nature. Among them were enlargement of the false tower at the top, more modern engines, installation of a radiogoniometer that could be controlled from inside the ship. Improvements and the installation of new air conditioning equipment meant a slight increase in displacement, and increase in the fuel stowage also increased the autonomy of these boats compared to the previous series. Their designed full load displacement was surfaced and submerged, but varied somewhat depending on the boat and the builder. The submarines were long, had a beam of and a draft of to .
For surface running, the boats were powered by two diesel engines, each driving one propeller shaft with overall power of . When submerged each propeller was driven by a electric motor. They could reach on the surface and underwater. On the surface, the Perla class had a range of at , submerged, they had a range of at .
The boats were armed with six internal torpedo tubes, four in the bow and two in the stern. One reload torpedo was carried for each tube, for a total of twelve. They were also armed with one deck gun for combat on the surface. The light anti-aircraft armament consisted of one or two pairs of machine guns.
Construction and career
Diaspro was built by CRDA at their shipyard in Trieste, laid on 29 September 1935, launched on 5 July 1936 and completed on 22 August 1936.
After delivery, Diaspro was assigned to the 35th Squadron (III Submarine Group) based at Messina. After a brief training, she carried out a long endurance cruise in the Mediterranean. During the Spanish Civil War she carried out two special missions under command of captain Giuseppe Mellina. During the first one, Diaspro sailed from Trapani on August 5, 1937, heading to patrol an area north of Cape Bon. During her patrol in the Strait of Sicily along the African coast, Diaspro attempted 25 attack attempts, and on August 13, 1937, launched torpedoes against two ships, one of them probably being the French cargo ship , but missed both times. Diaspro returned to Cagliari on August 15, 1937.
During the second one, Diaspro departed Naples on August 25 to patrol off Cape Oropesa. On September 1, 1937 Diaspro sighted near Benicarló a tanker heading to Alicante. Not being able to catch up with the ship under water, Diaspro attacked the tanker on the surface by launching two torpedoes. The ship crew spotted them, managed to maneuver and avoid them altogether, and made an attempt to ram the submarine. Diaspro fired two more torpedoes which hit the ship in the middle and sank it. The captain of the submarine believed this was a 6987 GRT Republican tanker heading to Alicante under the presumably false name , as the crew appeared to be Romanian. In reality the ship was recently acquired by a British-based operator, and the tanker was carrying petroleum from Constanta to Valencia. Diaspro returned to Naples on September 5, 1937.
At the time of Italy's entrance into World War II Diaspro was assigned to the 72nd Squadron (VII Submarine group) based at Cagliari. Her first mission in Tyrrhenian Sea was uneventful.
In July 1940 she first patrolled northwest of Asinara and then off the island of La Galite.
In August 1940 she patrolled off Cap Bougaroûn.
On September 1, during British Operation "Hats" Diaspro was on patrol in an area between Cape Spartivento and the island of La Galite. She managed to close to within ten miles from the British Force H naval group but could not attack because it was detected and repeatedly attacked by the aircraft of British aircraft carrier and forcing the submarine to dive.
On November 9, 1940, she left Cagliari to patrol off the island of La Galite along with four other submarines with the task of intercepting a British convoy, part of Operation "Coat" but failed to sight any enemy ships.
On November 14, she was deployed along with submarines and as a screen to British force part of Operation "White". Located about 315 miles from the island of La Galite, she was only able to detect a minor ship from the British force, but failed to attack it.
On January 21, 1941 Diaspro and patrolled off the northern Tunisian coast.
Diaspro was on three missions in February, May and June 1941, east of the island of La Galite, about twenty miles north of Cape Blanc, and south of Sardinia, respectively, but without any success.