Italian submarine Perla

Perla

Company type	Submarine
Industry	Naval military vessel
Founded	August 31, 1935 (1935-08-31) Monfalcone, Italy
Headquarters	Monfalcone , Italy
Products	Perla-class submarine

Italian submarine Perla was a Perla-class submarine constructed for the Royal Italian Navy (Regia Marina) during the 1930s. The vessel was named in honor of the gemstone Pearl.

Design and description

The Perla-class submarines were largely based on the earlier Sirena class design, with mainly enhancements incorporated. These upgrades included a larger false tower atop the conning tower, more advanced engines, and the addition of an internally operated radiogoniometer. Further improvements involved new air conditioning systems, which contributed to a slight increase in displacement. Additionally, expanded fuel storage enhanced the operational range compared to previous models. Their intended full load displacement was approximately 695 metric tons (684 long tons) on the surface and 855 metric tons (841 long tons) when submerged, though figures varied slightly depending on the specific vessel and shipyard. The submarines measured 197 feet 6 inches (60.20 m) in length, with a beam of 21 feet (6.4 m), and a draft ranging from 15 feet (4.6 m) to 15 feet 5 inches (4.70 m).

For surface propulsion, these submarines utilized two diesel engines, each connected to a separate propeller shaft, delivering a combined output between 675–750 hp (503–559 kW). Their maximum speeds reached 14 knots (26 km/h; 16 mph) when surfaced and 7.5 knots (13.9 km/h; 8.6 mph) submerged. The Perla class could cover up to 5,200 nautical miles (9,600 km; 6,000 mi) at a cruising speed of 8 knots (15 km/h; 9.2 mph) on the surface, while underwater endurance was limited to approximately 74 nautical miles (137 km; 85 mi) at 4 knots (7.4 km/h; 4.6 mph).

Armament consisted of six internal 53.3 cm (21.0 in) torpedo tubes—four located in the bow and two in the stern—with one reload torpedo available per tube, totaling twelve torpedoes onboard. Surface combat capability was provided by a single 100 millimetres (3.9 in) deck gun. Defensive anti-aircraft weaponry included one or two pairs of 13.2 millimetres (0.52 in) machine guns.

Construction and career

The submarine Perla was constructed by CRDA at their Monfalcone shipyard, with the keel laid on 31 August 1935. She was launched on 3 May 1936 and completed by 8 July 1936.

Following her delivery, Perla was assigned to the 35th Squadron (III Submarine Group) based in Messina, although she primarily operated out of Augusta. During the same year, she undertook an extensive training voyage visiting ports such as Tobruk, Benghazi, Bardia, Leros, and Rhodes in the Dodecanese, before returning to Augusta. In 1937, a similar training cruise took place within the Mediterranean, focusing mainly on domestic ports and concluding at Taranto.

In 1938, Perla was stationed at the Red Sea base in Massawa, Eritrea, tasked with evaluating submarine performance in tropical waters. Between 29 December 1938 and 24 January 1939, she, along with Glauco, conducted operations off the Somali coast.

During spring 1939, Perla and Gemma undertook a cruise in the Indian Ocean to assess their class's sailing and operational capabilities in warm seas amid monsoon conditions. The findings were unsatisfactory, revealing that rough seas hindered the use of onboard weapons and made maintaining periscope depth challenging. Additionally, issues with the air conditioning system were noted, including reported leaks of chloromethane.

Later in 1939, Perla returned temporarily to Italy for routine maintenance and repairs.

In the summer of that year, she participated in trials for a "bubble-free" torpedo launching system in Naples. The previous system emitted large air bubbles during torpedo deployment, which compromised stealth by revealing both the torpedoes' trajectory and the submarine’s position. The new system's tests yielded satisfactory outcomes.

At the onset of Italy's entry into World War II, Perla was again stationed at Massawa as part of the 82nd Squadron under Captain Mario Pouchain.

Initially ordered to remain at Massawa during the war’s early weeks, Viceroy Amedeo de Aosta requested deploying two additional submarines to operational zones. Rear Admiral Carlo Balsamo, commanding Massawa Base, approved this request, dispatching Perla alongside Archimede. Departing Massawa on the afternoon of 19 June 1940, Perla patrolled an area approximately 15 nautical miles from Ras-El Bir in the Gulf of Tadjoura. Her orders were to maintain position until 9 July and engage any enemy vessels encountered.

On 20 June, an electrician suffered heat stroke attributed to a malfunctioning air-conditioning system. Consequently, Captain Pouchain ordered inspections and maintenance; during the night of 21 June, the submarine surfaced to reduce poisoning risks. At dawn on 22 June, Perla submerged again; shortly thereafter multiple crew members fell ill with symptoms consistent with chloromethane poisoning—including hallucinations—and more cases developed over time. She continued patrolling her designated sector on 22–23 June. On 24 June, another submarine returned to Massawa with half its crew affected by chloromethane poisoning; Perla received orders to return immediately for repairs.

Turning back during the night of 24 June, by the following day more than half of her crew were ill and even the commander became incapacitated. Navigating submerged through the Bab-el-Mandeb Strait, internal temperatures reached as high as 64 °C. On 26 June, a sailor died and additional cases emerged. At sunset that day, upon surfacing, Perla encountered the British sloop HMS Shoreham, which promptly launched an attack. Forced to execute a crash dive, she remained submerged for several hours while enduring depth charge assaults but sustained only minor damage.

Later on 26 June, Perla surfaced again and resumed her journey back to Massawa. However, during the night approximately 20 miles from Sciab Sciach lighthouse, she ran aground. A distress message was sent requesting assistance; destroyers Leone and Pantera, along with torpedo boat Giovanni Acerbi, were dispatched. Due to engine failure, Leone had to return; meanwhile the other two vessels faced an advancing superior enemy force consisting of light cruiser HMNZS Leander and destroyers HMS Kingston and HMS Kandahar heading toward Perla. As HMS Kingston approached and opened fire, Perla returned fire but her gun jammed after two shots. Captain Pouchain ordered evacuation and destruction of all secret materials aboard. The arrival of two Italian air squadrons—eight SM-81 bombers—was crucial; they attacked enemy ships forcing them to retreat and preventing capture.

A rescue vessel arrived from Massawa on 15 July; within five days emergency repairs restored enough functionality for towing. On 20 July she was towed back to Massawa where extensive repairs rendered her nonoperational for an extended period.

By January 1941, anticipating the fall of Italian East Africa, plans were made to transfer submarines to Bordeaux to avoid loss or capture by British forces. Modifications were made to Perla including increased fuel capacity and removal of some torpedoes, gun ammunition, and non-essential equipment.

Under Captain Bruno Napp’s command, Perla departed Massawa on 1 March 1941. Shortly after leaving she survived an attack by a British Bristol Blenheim bomber armed with depth charges without sustaining damage. Traveling submerged through both the Red Sea and Bab-el-Mandeb Strait, she surfaced only upon entering the Indian Ocean. Proceeding southward east of Madagascar, she rendezvoused with German auxiliary cruiser Atlantis, which refueled and resupplied her.

Bernhard Rogge, commander of Atlantis, later recalled his surprise at encountering such a small coastal submarine with an exhausted crew; he advised Lt. Bruno Napp to consider seeking internment in Brazil or Argentina due to mission risks—advice politely declined by Napp who affirmed his commitment to orders.

Continuing northward over approximately 4,000 nautical miles before meeting with supply ship Northmark, Perla passed near Cape Verde Islands then between Canary Islands and Azores into the Bay of Biscay, ultimately reaching Bordeaux on 20 May 1941 after covering about 13,100 nautical miles over an 81-day voyage.

Following four months of repair work at Bordeaux base, she returned to service and departed on 20 September 1941 bound for the Mediterranean via the Strait of Gibraltar; she arrived at Cagliari on 3 October.

From 12 to 23 February 1942, Perla conducted her initial Mediterranean patrol off Cyrenaica.

She subsequently executed two similar patrols near Crete southwest of Gaudo: first from 29 March to 9 April and then from 16 to 28 April.

On 10 May she was assigned patrol duties off Kelibia along Tunisia’s coast; on the next day she sighted HMS Welshman east of La Galite island and launched two torpedoes which missed their target. She returned to base on 24 May.

On 6 July under Captain Gioacchino Ventura’s command, she sailed toward operational areas off Cyprus. On afternoon of 9 July near Beirut she sighted British corvette HMS Hyacinth and fired two torpedoes which failed to hit. The corvette retaliated with depth charges causing severe damage that forced Perla to surface.

Captain Ventura ordered abandonment and opening of Kingston valves; however some valves could not be opened due to damage causing slow sinking. A boarding party from Hyacinth boarded her vessel, closed valves preventing sinking further, then escorted her into Beirut harbor.

All crew members survived except officer Antonio De Maria who died during combat; survivors were taken prisoner by British forces.

Allied service

Renamed P-712, she was utilized by the Royal Navy for evaluation purposes regarding Italian submarine technology. In 1943 she was transferred to the Hellenic Navy where she received the name Matrozos, bearing pennant number Υ-7. She remained active with Greek naval forces until being decommissioned in 1947 and subsequently scrapped.

References

• Bagnasco, Erminio (1977). Submarines of World War Two. Annapolis, Maryland: Naval Institute Press. ISBN 0-87021-962-6.
• Chesneau, Roger, ed. (1980). Conway's All the World's Fighting Ships 1922–1946. Greenwich, UK: Conway Maritime Press. ISBN 0-85177-146-7.
• Rohwer, Jürgen (2005). Chronology of the War at Sea 1939–1945: The Naval History of World War Two (Third Revised ed.). Annapolis, Maryland: Naval Institute Press. ISBN 1-59114-119-2.
• Giorgerini, Giorgio (2002). Uomini sul fondo. Storia del sommergibilismo italiano dalle origini ad oggi (Second ed.). Mondadori. ISBN 8804505370.
• Pollina, Paolo (1963). I Sommergibili Italiani 1895–1962. Rome, Italy: SMM.