Onice was a built for the (Royal Italian Navy) during the 1930s. She played a minor role in the Spanish Civil War of 1936–1939 supporting the Spanish Nationalists. 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 . They had an operational diving depth of . Their crew numbered 45 officers and enlisted men. 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 Onice was built by OTO at their shipyard in Muggiano, laid on 27 August 1935, launched on 15 June 1936 and completed on 1 September 1936. After delivery, Onice was assigned to the 34th Squadron (III Submarine group) based at Messina. After a brief training, in 1937 she carried out a long endurance cruise in the Dodecanese, Tyrrhenian Sea and Ionian Sea. On August 12, 1937, she sailed from Naples under command of captain Mario Ricci to carry out a secret mission outside of Tarragona during the Spanish Civil War. The submarine fired two torpedoes at a tanker off Salou on August 17, but missed. On August 27, 1937 she returned to Naples. In