CB-class midget submarine

Caproni

Industry	Aerospace and defense manufacturing
Headquarters	Milan , Italy

Template:Infobox ship class overview

The CB class consisted of a series of midget submarines constructed for the Regia Marina during World War II. These vessels were also operated by various other naval forces and participated in operations within the Mediterranean Sea as well as the Black Sea.

Design and construction

Developed and manufactured by Caproni, these submarines served primarily in coastal defense roles, representing a notable advancement over the earlier CA class class. Each unit displaced 35.4 tons when surfaced and increased to 44.3 tons submerged. The submarines measured approximately 15 metres (49 ft 3 in) in length, with a beam spanning 3 metres (9 ft 10 in) and a draught of 2.05 metres (6 ft 9 in). Their propulsion system included a single Isotta Fraschini diesel engine paired with a Brown Boveri electric motor, together delivering around 130 horsepower (97 kW) to one shaft. This configuration enabled maximum speeds of roughly 7.5 knots (13.9 km/h; 8.6 mph) on the surface and 7 knots (13 km/h; 8.1 mph) underwater. Armament comprised two externally mounted 450 millimetres (18 in) torpedo tubes, which could be reloaded without drydocking the vessel; alternatively, these torpedoes could be substituted with two naval mines. The crew complement was four personnel, who navigated using a compact conning tower.

Service

Out of an order for seventy-two vessels placed with Caproni in Milan, only 22 were actually started. Prior to the Italian Armistice, twelve boats were finished, while nine were completed subsequently.

Black Sea

Italian sailors from the Quarta Flottiglia MAS aboard a CB-class submarine stationed in Crimea

The initial six submarines, finalized in 1941, were transported via rail to the Black Sea following a request from Nazi Germany for Italian naval assistance on the Eastern Front. They set off on 25 April 1942 and arrived at the Romanian port of Constanța by 2 May. These units were organized into the 1st Squadriglia Sommergibili CB, commanded overall by Francesco Mimbelli. Engaged against the Soviet Black Sea Fleet, CB-5 was lost near Yalta in June 1942, reportedly sunk either by Soviet aircraft or a torpedo boat. Later in 1942, the remaining five submarines underwent refurbishment at the Constanța Shipyard in Romania. On 26 August 1943, CB-4 successfully torpedoed and destroyed the Soviet Shchuka-class Shch-203.

Black Sea submarines under Romanian command, late 1943

Following Italy’s armistice with the Allies in September 1943, the five Black Sea submarines (CB-1, CB-2, CB-3, CB-4, and CB-6) were handed over to the Royal Romanian Navy. These vessels were deliberately sunk in the Black Sea during August 1944 after the occurrence of King Michael's Coup.

In August 1944, Soviet forces seized four of these submarines (CB-1, CB-2, CB-3, and CB-4) and commissioned them on 20 October as TM-4, TM-5, TM-6, and TM-7. They were officially removed from service on 16 February 1945 and subsequently dismantled.

Mediterranean

Initially, the first six vessels were deployed as anti-submarine units near Naples and Salerno, but these efforts proved ineffective. In early 1942, they were reassigned to operations in the Black Sea. The second group of submarines (CB-7 through CB-12) was finalized just prior to the Armistice in August 1943. Except for CB-7, which was later dismantled for spare parts, all remained under Italian control when Italy aligned with the Allies. Submarines CB-13, CB-14, CB-15, and CB-16 fell into German hands; however, with the exception of CB-16, they were destroyed by Allied air strikes. Assigned to the 10th Flotilla of the National Republican Navy—the naval force of the Italian Social Republic—CB-16 experienced a crew mutiny resulting in its surrender to British forces. The final squadron undertaken conducted reconnaissance patrols and facilitated saboteur landings. Among these, CB-17 was lost during an aerial assault, CB-18 was deliberately sunk by its crew, CB-19 was handed over to Allied forces, CB-20 was seized by Yugoslav Partisans, CB-21 suffered accidental sinking after a collision with a German landing craft, and CB-22 was either destroyed by air attack or scuttled by her own crew.

List of submarines

Submarine	Completion Date	Operational History / Outcome
CB-1	27 January 1941	Redeployed to the Black Sea; transferred to Romania post-September 1943. Scuttled in August 1944, subsequently raised by the USSR, commissioned as TM-4, dismantled in 1945
CB-2	27 January 1941	Moved to Black Sea duties; passed to Romania after September 1943. Scuttled August 1944, salvaged by USSR, renamed TM-5, scrapped in 1945
CB-3	10 May 1941	Operated in Black Sea; handed over to Romania post-September 1943. Scuttled August 1944, raised by USSR, designated TM-6, scrapped 1945
CB-4	10 May 1941	Assigned to Black Sea fleet; transferred to Romania after September 1943. Scuttled August 1944, recovered by USSR, renamed TM-7, dismantled in 1945
CB-5	10 May 1941	Operated in Black Sea; sunk near Yalta on 13 June 1942 by Soviet aircraft or torpedo boat
CB-6	10 May 1941	Deployed in Black Sea; transferred to Romania post-September 1943. Scuttled August 1944
CB-7	1 August 1943	Seized by Germany at Pola in September 1943; dismantled for parts
CB-8	1 August 1943	Surrendered to British forces in 1943; scrapped in 1948
CB-9	1 August 1943	Turned over to Britain in 1943; dismantled in 1948
CB-10	1 August 1943	Surrendered to Britain during 1943; scrapped in 1948
CB-11	24 August 1943	Handed over to British authorities in 1943; scrapped by 1948
CB-12	24 August 1943	Surrendered to Britain in 1943; dismantled in 1948
CB-13	Late 1943	Captured by German forces in 1943; transferred to Italian Social Republic, destroyed by Allied air raid on 23 March 1945
CB-14	Late 1943	Taken over by Germany in 1943; assigned to Italian Social Republic, sunk during an air attack
CB-15	Late 1943	Captured by Germany and allocated to Italian Social Republic; lost during an aerial bombardment
CB-16	Late 1943	Seized by Germans and transferred to Italian Social Republic; sunk during air raid
CB-17	Late 1943	German-captured and assigned to Italian Social Republic; sunk by Allied aircraft on April 3, 1945
CB-18	Late 1943	Taken over by Germany and allocated to Italian Social Republic; sunk on March 31, 1945
CB-19	Late 1943	Captured and transferred to Italian Social Republic; dismantled in 1947
CB-20	Late 1943	Seized by Germany and assigned to Italian Social Republic. Captured by Yugoslav Partisans at Pula at war’s end. Served actively with the Yugoslav Navy from 1950–1957 as P-901. Donated to the Technical Museum, Zagreb in Zagreb in 1959
CB-21	Late 1943	German-captured and transferred to Italian Social Republic; accidentally rammed and sunk by a Marinefährprahm on April 29, 1945
CB-22		Captured by Germany in ’43, either destroyed during an air raid or scuttled. Wreck later salvaged and preserved in Trieste

See also

• Italian submarines of World War II

Further reading

• Chesneau, Roger (ed.). Conway's All the World's Fighting Ships 1922–46. Conway Maritime Press Ltd, 1997. ISBN 978-0851771465.
• Kemp, Paul. Underwater Warriors. Cassell, 1996. ISBN 978-0304354542.

External links

• Classe CB – Official site of the Marina Militare