The ''Calvi'' class was a

class Class, Classes, or The Class may refer to: Common uses not otherwise categorized * Class (biology), a taxonomic rank * Class (knowledge representation), a collection of individuals or objects * Class (philosophy), an analytical concept used d ...

of three

submarine A submarine (often shortened to sub) is a watercraft capable of independent operation underwater. (It differs from a submersible, which has more limited underwater capability.) The term "submarine" is also sometimes used historically or infor ...

s built by Oderno-Terni-Orlando in

Genoa Genoa ( ; ; ) is a city in and the capital of the Italian region of Liguria, and the sixth-largest city in Italy. As of 2025, 563,947 people live within the city's administrative limits. While its metropolitan city has 818,651 inhabitan ...

for the

Royal Italian Navy The , ) (RM) or Royal Italian Navy was the navy of the Kingdom of Italy () from 1861 to 1946. In 1946, with the birth of the Italian Republic (''Repubblica Italiana''), the changed its name to ''Marina Militare'' ("Military Navy"). Origins ...

(). The submarines were built in 1935, and all three served in the Mediterranean at the start of the

Second World War World War II or the Second World War (1 September 1939 – 2 September 1945) was a World war, global conflict between two coalitions: the Allies of World War II, Allies and the Axis powers. World War II by country, Nearly all of the wo ...

. The boats were transferred to the

BETASOM BETASOM (an Italian language acronym of ''Bordeaux Sommergibile'' or ''Sommergibili'') was a submarine base established at Bordeaux, France by the '' Regia Marina'' during the Second World War. From this base, Italian submarines participated in t ...

Atlantic submarine base at

Bordeaux Bordeaux ( ; ; Gascon language, Gascon ; ) is a city on the river Garonne in the Gironde Departments of France, department, southwestern France. A port city, it is the capital of the Nouvelle-Aquitaine region, as well as the Prefectures in F ...

in August 1940. In December 1941 the boats were used for a rescue mission of 254 sailors from the sunken . After ''Calvi'' had been sunk, ''Finzi'' and ''Tazzoli'' were selected for conversion to " transport submarines" in order to exchange rare or irreplaceable trade goods with

Japan Japan is an island country in East Asia. Located in the Pacific Ocean off the northeast coast of the Asia, Asian mainland, it is bordered on the west by the Sea of Japan and extends from the Sea of Okhotsk in the north to the East China Sea ...

. Cargo capacity of 160 tons reduced reserve buoyancy from 20–25% to 3.5–6%; and armament was reduced to defensive machine guns.

Design and description

The ''Calvi'' class was an improved and enlarged version of the preceding

submarine cruiser A cruiser submarine was a very large submarine designed to remain at sea for extended periods in areas distant from base facilities. Their role was analogous to surface cruisers; 'cruising' distant waters, commerce raiding, and otherwise operatin ...

s. They displaced surfaced and submerged. The submarines were long, had a

beam Beam may refer to: Streams of particles or energy *Light beam, or beam of light, a directional projection of light energy **Laser beam *Radio beam *Particle beam, a stream of charged or neutral particles **Charged particle beam, a spatially lo ...

of and a

draft Draft, the draft, or draught may refer to: Watercraft dimensions * Draft (hull), the distance from waterline to keel of a vessel * Draft (sail), degree of curvature in a sail * Air draft, distance from waterline to the highest point on a v ...

of . They had an operational diving depth of . Their crew numbered 77 officers and enlisted men.Chesneau, p. 305 For surface running, the boats were powered by two

diesel engine The diesel engine, named after the German engineer Rudolf Diesel, is an internal combustion engine in which Combustion, ignition of diesel fuel is caused by the elevated temperature of the air in the cylinder due to Mechanics, mechanical Compr ...

s, each driving one

propeller shaft A drive shaft, driveshaft, driving shaft, tailshaft (Australian English), propeller shaft (prop shaft), or Cardan shaft (after Girolamo Cardano) is a component for transmitting mechanical power, torque, and rotation, usually used to connect o ...

. When submerged each propeller was driven by a

electric motor An electric motor is a machine that converts electrical energy into mechanical energy. Most electric motors operate through the interaction between the motor's magnetic field and electric current in a electromagnetic coil, wire winding to gene ...

. They could reach on the surface and underwater. On the surface, the ''Calvi'' class had a range of at ; submerged, they had a range of at .Bagnasco, p. 152 The boats were armed with eight

torpedo tube A torpedo tube is a cylindrical device for launching torpedoes. There are two main types of torpedo tube: underwater tubes fitted to submarines and some surface ships, and deck-mounted units (also referred to as torpedo launchers) installed aboa ...

s, four each in the bow and in the stern for which they carried a total of 16

torpedo A modern torpedo is an underwater ranged weapon launched above or below the water surface, self-propelled towards a target, with an explosive warhead designed to detonate either on contact with or in proximity to the target. Historically, such ...

es. They were also armed with a pair of

deck guns A deck gun is a type of naval artillery mounted on the deck of a submarine. Most submarine deck guns were open, with or without a shield; however, a few larger submarines placed these guns in a turret. The main deck gun was a dual-purpose w ...

, one each fore and aft of the

conning tower A conning tower is a raised platform on a ship or submarine, often armoured, from which an officer in charge can conn (nautical), conn (conduct or control) the vessel, controlling movements of the ship by giving orders to those responsible for t ...

, for combat on the surface. Their anti-aircraft armament consisted of two twin-gun mounts for machine guns.

Ships

''Pietro Calvi''

''Pietro Calvi'' (

pennant number In the Royal Navy and other navies of Europe and the Commonwealth of Nations, ships are identified by pennant number (an internationalisation of ''pendant number'', which it was called before 1948). Historically, naval ships flew a flag that iden ...

CV) was launched 31 March 1935. During the Spanish Civil War, she unsuccessfully fired a pair of torpedoes each at the

mail steamer Packet boats were medium-sized boats designed mainly for domestic mail and freight transport in European countries and in North American rivers and canals. Eventually including basic passenger accommodation, they were used extensively during t ...

and the 3946 mail steamer during a patrol on 1–17 January 1937. During the night of 12/13 January she bombarded the port of

Valencia Valencia ( , ), formally València (), is the capital of the Province of Valencia, province and Autonomous communities of Spain, autonomous community of Valencian Community, the same name in Spain. It is located on the banks of the Turia (r ...

. The first patrol during the Second World War was from

Liguria Liguria (; ; , ) is a Regions of Italy, region of north-western Italy; its Capital city, capital is Genoa. Its territory is crossed by the Alps and the Apennine Mountains, Apennines Mountain chain, mountain range and is roughly coextensive with ...

to the

Atlantic Ocean The Atlantic Ocean is the second largest of the world's five borders of the oceans, oceanic divisions, with an area of about . It covers approximately 17% of Earth#Surface, Earth's surface and about 24% of its water surface area. During the ...

, and lasted from 3 July to 6 August 1940. After overhaul at La Spezia, ''Calvi'' sailed on 6 October 1940 for a second Atlantic patrol, reaching Bordeaux on 23 October. ''Calvi'' suffered storm damage during its third patrol off the

British Isles The British Isles are an archipelago in the Atlantic Ocean, North Atlantic Ocean off the north-western coast of continental Europe, consisting of the islands of Great Britain, Ireland, the Isle of Man, the Inner Hebrides, Inner and Outer Hebr ...

from 3 to 31 December 1940. The fourth patrol was between the

Canary Islands The Canary Islands (; ) or Canaries are an archipelago in the Atlantic Ocean and the southernmost Autonomous communities of Spain, Autonomous Community of Spain. They are located in the northwest of Africa, with the closest point to the cont ...

and the

Azores The Azores ( , , ; , ), officially the Autonomous Region of the Azores (), is one of the two autonomous regions of Portugal (along with Madeira). It is an archipelago composed of nine volcanic islands in the Macaronesia region of the North Atl ...

from 31 March to 13 May 1941. ''Calvi'' sailed on 1 August 1941 for a fifth patrol off the Canary Islands. During the sixth patrol from 7 to 29 December 1941 ''Calvi'', ''Finzi'' and ''Tazzoli'' rescued sailors of the sunken raider ''Atlantis''. The seventh patrol was off

Brazil Brazil, officially the Federative Republic of Brazil, is the largest country in South America. It is the world's List of countries and dependencies by area, fifth-largest country by area and the List of countries and dependencies by population ...

from 7 March to 29 April 1942. ''Calvi'' sailed on 2 July 1942 for its eighth patrol. ''Calvi'' was rammed and sunk on 14 July 1942 by convoy SL 115 escort . Three officers and 32 sailors survived.

''Giuseppe Finzi''

''Giuseppe Finzi'' (pennant number FZ) was launched 29 June 1935. The first war patrol was from

Cagliari Cagliari (, , ; ; ; Latin: ''Caralis'') is an Comune, Italian municipality and the capital and largest city of the island of Sardinia, an Regions of Italy#Autonomous regions with special statute, autonomous region of Italy. It has about 146,62 ...

to the Atlantic, and lasted from 5 June to 10 July 1940. The submarine sailed on 7 September 1940 and passed the

Strait of Gibraltar The Strait of Gibraltar is a narrow strait that connects the Atlantic Ocean to the Mediterranean Sea and separates Europe from Africa. The two continents are separated by 7.7 nautical miles (14.2 kilometers, 8.9 miles) at its narrowest point. Fe ...

on 13 September for an Atlantic patrol to

, France, on 29 September. Admiral

Karl Dönitz Karl Dönitz (; 16 September 1891 – 24 December 1980) was a German grand admiral and convicted war criminal who, following Adolf Hitler's Death of Adolf Hitler, suicide, succeeded him as head of state of Nazi Germany during the Second World ...

visited ''Giuseppe Finzi'' on 30 September to welcome sailors to the German base. The third patrol near the British Isles from 24 October to 4 December 1940 revealed that the diesel engine air intake was too exposed for North Atlantic winter weather. The fourth patrol was near the

from 10 March to 17 April 1941 and the fifth patrol was off Gibraltar in August. During the sixth patrol from 7 to 29 December 1941 , ''Giuseppe Finzi'' and rescued sailors of the sunken German

commerce raider Commerce raiding is a form of naval warfare used to destroy or disrupt logistics of the enemy on the open sea by attacking its merchant shipping, rather than engaging its combatants or enforcing a blockade against them. Privateering is a fo ...

. The submarine sailed for

Operation Neuland Operation Neuland was the code name of the Kriegsmarine extension of unrestricted submarine warfare into the Caribbean Sea during World War II. German U-boats demonstrated range to disrupt British petroleum supplies and American aluminum suppli ...

on 6 February 1942 and returned on 31 March. She returned to the

Caribbean Sea The Caribbean Sea is a sea of the Atlantic Ocean, North Atlantic Ocean in the tropics of the Western Hemisphere, located south of the Gulf of Mexico and southwest of the Sargasso Sea. It is bounded by the Greater Antilles to the north from Cuba ...

for an eighth patrol from 6 June to 18 August 1942. On 26 November 1942 ''Giuseppe Finzi'' sailed for a ninth patrol to Brazil; but mechanical problems required return to base on 10 December. The boat patrolled the

West African West Africa, also known as Western Africa, is the westernmost region of Africa. The United Nations defines Western Africa as the 16 countries of Benin, Burkina Faso, Cape Verde, The Gambia, Ghana, Guinea, Guinea-Bissau, Ivory Coast, Liberia, Ma ...

coast from 11 February to 18 April 1943. Conversion to a transport submarine was never completed, and the boat was seized by the Germans on 9 September 1943 when Italy surrendered to the

Allies An alliance is a relationship among people, groups, or states that have joined together for mutual benefit or to achieve some common purpose, whether or not an explicit agreement has been worked out among them. Members of an alliance are calle ...

. Renamed ''UIT21'' in German service, she was scuttled at

Le Verdon-sur-Mer Le Verdon-sur-Mer (, ; ) is a commune in the Gironde department in Nouvelle-Aquitaine in southwestern France. History In the 11th century, the territory housed the priory of Saint-Nicholas de Grave, dependent on Cluny. It housed the monks in c ...

on 25 August 1944 to prevent her capture by the advancing Allied forces.

''Enrico Tazzoli''

''Enrico Tazzoli'' (pennant number TZ) was launched 14 October 1935. It was named after Enrico Tazzoli, a martyr of the Italian wars of independence. The first wartime patrol was off the coast of

North Africa North Africa (sometimes Northern Africa) is a region encompassing the northern portion of the African continent. There is no singularly accepted scope for the region. However, it is sometimes defined as stretching from the Atlantic shores of t ...

from 21 June to 2 July 1940. The second was an unsuccessful attempt to pass the

from 30 July to 9 August 1940. After overhaul at La Spezia, ''Enrico Tazzoli'' sailed on 2 October 1940 and passed the Strait of Gibraltar on 7 October for an Atlantic patrol to Bordeaux on 24 October. The fourth patrol was off the British Isles from 13 December 1940 to 6 January 1941. The boat sailed on 7 April 1941 to patrol between

Freetown Freetown () is the Capital city, capital and largest city of Sierra Leone. It is a major port city on the Atlantic Ocean and is located in the Western Area of the country. Freetown is Sierra Leone's major urban, economic, financial, cultural, e ...

and the Azores; and shot down an attacking

Bristol Blenheim The Bristol Blenheim is a British light bomber designed and built by the Bristol Aeroplane Company, which was used extensively in the first two years of the Second World War, with examples still being used as trainers until the end of the war. ...

while returning to port on 23 May. The sixth patrol was again off Freetown from 15 July to 11 September 1941. During the seventh patrol from 7 to 27 December 1941 , and ''Tazzoli'' rescued sailors of the sunken German

. The submarine sailed for

on 2 February 1942 and returned on 31 March. The ninth patrol was again to the

Caribbean The Caribbean ( , ; ; ; ) is a region in the middle of the Americas centered around the Caribbean Sea in the Atlantic Ocean, North Atlantic Ocean, mostly overlapping with the West Indies. Bordered by North America to the north, Central America ...

from 18 June to 5 September 1942; and the tenth patrol was to Brazil from 14 November 1942 to 2 February 1943. After conversion to a transport submarine for blockade-running between Europe and the

Far East The Far East is the geographical region that encompasses the easternmost portion of the Asian continent, including North Asia, North, East Asia, East and Southeast Asia. South Asia is sometimes also included in the definition of the term. In mod ...

, ''Enrico Tazzoli'' sailed for Japan on 16 May 1943 and was sunk by aircraft in the

Bay of Biscay The Bay of Biscay ( ) is a gulf of the northeast Atlantic Ocean located south of the Celtic Sea. It lies along the western coast of France from Point Penmarc'h to the Spanish border, and along the northern coast of Spain, extending westward ...

on 23 May.Brice, pp. 131–133

References

Notes

Sources

* * * * * * *

External links

Classe Pietro Calvi
Marina Militare website {{WWII Italian ships Submarine classes Submarines of the Regia Marina Ships built by OTO Melara