The Mediterranean U-boat Campaign lasted from about 21 September 1941 to 19 September 1944 during the Second World War. Malta was an active British base strategically located near supply routes from Europe to North Africa. Axis supply convoys across the Mediterranean Sea suffered severe losses, which in turn threatened the fighting ability of the Axis armies in North Africa. The Allies were able to keep their North African armies supplied. The Kriegsmarine tried to isolate Malta but later it concentrated its U-boat operations on disrupting Allied landing operations in southern Europe.
Some 60 German U-boats made the hazardous passage into the Mediterranean Sea from 1941; however, none successfully returned to the Atlantic. Karl Dönitz, the Commander-in-Chief, U-boats, Befehlshaber der Unterseeboote (BdU) was always reluctant to send his boats into the Mittelmeer but he recognised that natural bottlenecks such as the Straits of Gibraltar were more likely to result in shipping being found and attacked than relying on finding it in the vast Atlantic Ocean.
The U-boats were sent to assist the Italians, although many were attacked in the Strait of Gibraltar and nine were sunk while attempting the passage and ten more were damaged. The Mediterranean is a clear and calm body of water which made escape more difficult for the U-boats. The Axis failed in their objective.
Prior Experience
The Kriegsmarine had acquired some knowledge of the area. Dönitz was an officer aboard UB-68 which had been sunk in the region in World War I. U-boats had also served in the Spanish Civil War. The Republicans, with twelve submarines, opposed the Nationalists, who had none; the presence of German U-boats was most welcome. The first two vessels, U-33 and U-34, under the codename Training Exercise Ursula, left Wilhelmshaven on 20 November 1936. Both submarines sailed down the English Channel and slipped into the Mediterranean on the night of 27 November. They were soon in action, U-34 fired a single torpedo at a Republican destroyer in the evening of 1 December. The projectile missed, impacting on rocks. The boat, under Leutnant zur See Harald Grosse, tried again on 5 and 8 December, with an equal lack of success. U-33 fared no better; her commander was frustrated by the absence of target identification or defensive movement of his intended victims. Only one vessel was sunk by the U-boats, the Republican submarine C-3, which was attacked by U-34 on 12 December.
The early years
By October 1939, Dönitz had decided to use three longer-range boats to intercept the first Allied convoys of the war. U-25, U-26 and U-53 were to rendezvous southwest of Ireland before attempting to force the Straits and attack the convoys in the Mediterranean. Things went quickly wrong, U-25 was diverted to a convoy south-west of Lisbon. After an abortive torpedo attack on a steamer on 31 October, Viktor Schütze, U-25's commander, surfaced and proceeded to sink his target with fire from his deck gun. This course of action caused a crack in a vital part of the submarine, obliging the boat to return to Germany. U-53 ran low on fuel after shadowing a convoy in the Bay of Biscay and was also forced to return. U-26, was compelled by a combination of unsuitable weather, searchlights and British anti-submarine patrols, to abandon an attempt to lay mines near Gibraltar harbour. The boat sailed through the Straits on the surface and claimed but a solitary ship sunk in the Mediterranean. This 'sinking' was not confirmed by post-war analysis.
U-26 headed back through the Straits, arriving in Wilhelmshaven on 5 December 1939; the only U-boat to enter and leave the Mediterranean in the war. This mission was summed-up in the BdU Kriegstagebuch (KTB) War Diary,
It was a mistake to send U-25, U-26 and U-53 into the Mediterranean. U-25 had to return before she ever got there, U-53 did not get through and U-26 hardly encountered any shipping worth mentioning. This patrol shows all the disadvantages of a long outward passage.|KTB
Many attacks mentioned were gun actions or ramming, particularly at the eastern end of the Mediterranean. This was because the potential target was "unworthy or [a] difficult torpedo target".
Afrika Korps
The 23rd U-boat Flotilla was established in September 1941 to intercept coastal shipping supplying Allied forces in the Siege of Tobruk. U-boats patrolled the eastern Mediterranean from the 23rd flotilla base on Salamis Island in Greece. On 7 December, control of the 23rd Flotilla was transferred from Kernével to The Commander in Chief in the South (Oberbefehlshaber Süd, OB Süd) Albert Kesselring. Additional bases were established in Pula in Croatia and La Spezia in northern Italy as more U-boats were ordered to the Mediterranean, until focus shifted to the western Atlantic through the Second Happy Time.
- U-371 passed Gibraltar on 21 September 1941.
- U-559 passed Gibraltar on 26 September 1941, and sank HMAS Parramatta on 27 November, the 3,059-ton Shuntien of convoy TA 5 on 23 December, and the 2,487-ton Warszawa of convoy AT 6 on 26 December.
- U-97 passed Gibraltar on 27 September 1941, sank the 1,208-ton Samos and the 758-ton Pass of Balmaha on 17 October.
- U-331 passed Gibraltar on 30 September, destroyed a 372-ton British landing craft on 10 October, and sank HMS Barham on 25 November 1941.
- U-75 passed Gibraltar on 3 October, sank two 372-ton British landing craft on 12 October, and sank the 1,587-ton Volo of convoy ME 8 before being sunk by convoy escort HMS Kipling on 28 December 1941.
- U-79 passed Gibraltar on 5 October, damaged HMS Gnat on 21 October, and was sunk on 23 December 1941 by Royal Navy destroyers.
- U-205 passed Gibraltar on 11 November 1941.
- U-81 passed Gibraltar on 12 November and sank HMS Ark Royal on 13 November 1941.
- U-433 was sunk near Gibraltar on 16 November 1941 by HMS Marigold.
- U-565 passed Gibraltar on 16 November 1941.
- U-431 passed Gibraltar on 24 November 1941 and damaged the 3,560-ton Myriel on 13 December.
- U-557 passed Gibraltar on 26 November, sank the 4,032-ton Fjord on 2 December, then sank HMS Galatea on 15 December, and was sunk on 16 December 1941 by the Italian torpedo boat Orione.
- U-562 passed Gibraltar on 27 November 1941 and sank the 4,274-ton Grelhead on 2 December.
- U-95 was torpedoed by the Dutch submarine O 21 while passing Gibraltar on 28 November 1941.
- U-652 passed Gibraltar on 29 November 1941, sank the 1,595-ton Saint Denis on 9 December, and sank the 6,557-ton Varlaam Avanesov on 19 December.
- U-372 passed Gibraltar on 8 December 1941.
- U-375 passed Gibraltar on 9 December 1941.
- U-453 passed Gibraltar on 9 December 1941 and sank the Spanish ship Badalona on 13 December.
- U-374 sank the trawler HMS Lady Shirley and the patrol yacht HMS Rosabelle while passing Gibraltar on 10 December 1941 and was torpedoed by HMS Unbeaten on 12 January 1942.
- U-568 passed Gibraltar on 10 December 1941 and sank HMS Salvia on 24 December
- U-74 passed Gibraltar on 15 December 1941.
- U-77 passed Gibraltar on 16 December 1941 and damaged HMS Kimberley on 12 January 1942.
- U-83 passed Gibraltar on 18 December 1941.
- U-573 passed Gibraltar on 18 December 1941 and sank the 5,289-ton Hellen on 21 December.
- U-451 was sunk by Fairey Swordfish from 812 Naval Air Squadron while passing Gibraltar on 21 December 1941.
- U-133 passed Gibraltar on 21 December 1941.
- U-577 passed Gibraltar on 23 December 1941 and was sunk by aircraft on 9 January 1942.
- U-73 passed Gibraltar on 14 January.
- U-561 passed Gibraltar on 15 January 1942
Second Happy Time
La Spezia became headquarters when the Mediterranean U-boats were reorganized as the 29th U-boat Flotilla in May 1942. No more U-boats were assigned to the Mediterranean from mid-January to early October 1942 as opportunities along the east coast of North America seemed more productive while the Afrika Korps was successfully advancing on Egypt. The 29th flotilla focused on convoys supplying Malta and British forces on the Egyptian coast. For sustained operations, U-boats spent approximately one-third of the time on patrol stations, one-third in transit to and from base for routine provisioning and refueling, and one-third undergoing major overhaul or battle repair. 29th flotilla target strength of twenty U-boats enabled a routine patrol strength of three U-boats from Salamis in the eastern Mediterranean, and three from La Spezia in the western Mediterranean. Loss of U-372 and U-568 in twelve-hour sustained attacks demonstrated vulnerability of independent U-boat patrols to a team of destroyers which could hunt a submerged U-boat to exhaustion of air and battery power, rather than moving on after a few attacks.
- U-73 sank HMS Eagle on 11 August 1942.
- U-74 was sunk on 2 May 1942 by aircraft and destroyers.
- U-77 sank HMS Grove on 12 June. U-77 then sank sailing ships Vassiliki on 22 July, Toufic El Rahman on 24 July, Fany on 30 July, and Saint Simon on 1 August. U-77 continued patrolling the coast of Cyprus, Palestine and Lebanon damaging Adnan and sinking Ezzet on 6 August, Kharouf on 10 August and Daniel on 16 August 1942.
- U-81 sank the 6,018-ton Caspia, the French trawler Viking, and sailing ships Bab el Faraq and Farouh el Kher on 16 April 1942. U-81 sank sailing ships Hefz el Rahman on 19 April, Aziza and the El Saadiah on 22 April, and then 2,073-ton Havre of convoy AT 49 on 10 June 1942.
- U-83 damaged the 2,590-ton Crista on 17 March 1942, sank the 100-ton Esther and the 231-ton Said on 8 June, the 175-ton Typhoon on 9 June, the Q-ship HMS Farouk on 13 June, and the 5,875-ton Princess Marguerite on 17 August 1942.
- U-97 sank the 1,755-ton Memas and the 1,433-ton Zealand from convoy Metril on 28 June 1942, and sank the 786-ton Marilyse Moller on 1 July.
- U-133 sank HMS Gurkha on 17 January 1942 and sank after striking a mine off Salamis on 12 March 1942.
- U-205 sank the 2,623-ton Slavol on 26 March 1942, and sank HMS Hermione on 16 June 1942.
- U-331 shelled the Beirut electric power station in April 1942.
- U-371
- U-372 sank HMS Medway on 30 June 1942, and was hunted to exhaustion on 3 August 1942.
- U-375 sank the 1,376-ton Hero on 6 July 1942, sank the 87-ton Amina and the 176-ton Ikbal on 30 July, and damaged the 6,288-ton Empire Kumari of convoy LW 38 on 26 August. She also sank the 558-ton Arnon, the 38-ton Miriam and the 108-ton Salina on 3 September. She then sank the 113-ton Turkian on 6 September 1942.
- U-431 sank the trawler HMS Sotra on 29 January 1942, she then sank the 4,216-ton Eocene of convoy AT 46 on 20 May, and damaged LCT-119 on 20 June 1942.
- U-453 damaged the hospital ship Somersetshire on 7 April 1942.
- U-559 sank the 4,681-ton Athene and damaged the 5,917-ton Brambleleaf of convoy AT 49 on 10 June 1942.
- U-561 planted a minefield at the mouth of the Suez Canal, sinking the 6,692-ton Mount Olympus, and damaging the 5,062-ton Hav and the 4,043-ton Fred.
- U-562 damaged the 3,359-ton Adinda on 24 July 1942.
- U-565 sank HMS Naiad on 11 March 1942 and the 1,361-ton Kirkland of convoy TA 36 on 23 April.
- U-568 was hunted to exhaustion on 28 May 1942.
- U-573 was interned in Spain following bomb damage on 1 May 1942.
- U-652 sank HMS Heythrop on 20 March 1942, sank HMS Jaguar on 26 March and was sunk on 2 June 1942 by 815 Naval Air Squadron.
Allied invasion of North Africa
More U-boats were assigned to the 29th flotilla when improved anti-submarine warfare (ASW) measures along the east coast of North America ended the Second Happy Time. When a Short Sunderland found U-559, the aircraft summoned five destroyers able to maintain contact and drop 150 depth charges over ten hours, until the submarine attempted to sneak away on the surface at night. Waiting destroyers open fire as soon as the U-boat surfaced and the U-boat crew abandoned ship. The Royal Navy boarded the sinking U-boat and recovered German code documents before U-559 sank.
The Second Battle of El Alamein prompted a concentration of U-boats in the western Mediterranean, in anticipation of Allied amphibious invasion. Five U-boats made contact with Operation Torch convoys, and two wolfpacks assembled near the invasion points. U-73, U-81, U-458, U-565, U-593, U-595, U-605 and U-617 assembled around Oran as Gruppe Delphin (Group Dolphin); U-77, U-205, U-331, U-431, U-561 and U-660 assembled around Algiers as Gruppe Hai (Group Shark). Five U-boats were sunk opposing the invasion.