Mediterranean U-boat Campaign (World War II)

Mediterranean U-boat Campaign
Part of the Battle of the Mediterranean of World War II

U-617 aground near Mellila, Morocco at position 35°23′N 3°16′W / 35.38°N 03.27°W / 35.38; -03.27 after British air attack 12 September 1943
Date21 September 1941 to May 1944
LocationMediterranean Sea
Result Allied Victory
 Royal Navy
 Royal Australian Navy
 United States Navy
Other Allied navies
 Regia Marina
62 U-boats
Casualties and losses
95 merchant ships sunk
24 major warships sunk
62 U-boats lost

The Mediterranean U-boat Campaign lasted approximately from 21 September 1941 to 19 September 1944 during World War II. Malta was an active British base strategically located near supply routes from Europe to North Africa. As a result, Axis supply convoys across the Mediterranean Sea suffered severe losses, which in turn threatened the fighting ability of the Axis armies in North Africa. At the same time the Allies were able successfully to keep their North African armies supplied. The Kriegsmarine initially aimed, unsuccessfully, to isolate Malta but later it concentrated its U-boat operations on disrupting Allied landings operations in southern Europe.

Some 60 German U-boats made the hazardous passage into the Mediterranean Sea in World War II. Only one completed the journey both ways.[1][2] 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 'choke points' 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, of which nine were sunk while attempting passage and 10 more were damaged. The Mediterranean is a clear and calm body of water which made escape more difficult for the U-boats.[3] The Axis failed in their objective.

Previous 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.[4]

U-boats had also served in the Spanish Civil War. The Republicans, with twelve submarines, opposed the Nationalists, who had none; so 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 began to go wrong from the outset when U-25 was diverted to a convoy southwest of Lisbon. After an unsuccessful 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.
This only left U-26, which compelled by a combination of unsuitable weather, searchlights and British anti-submarine patrols, abandoned any attempt at laying mines before Gibraltar harbour. The boat sailed through the Straits while 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 Wilhelshaven on 5 December 1939; the only U-boat to successfully enter and leave the Mediterranean in World War II.[5][6]

This mission was summed-up in the BdU Kriegstagebuch (KTB) War Diary thus:[7]

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.

Many attacks mentioned below were as the result of 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."[8]

Supporting the Afrika Korps

The 23rd U-boat Flotilla was established in September 1941 to intercept coastal shipping sustaining Allied forces through the siege of Tobruk.[9] 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 German High Command in Italy headed by 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.[10]

Second Happy Time

La Spezia became headquarters when the Mediterranean U-boats were reorganized as the 29th U-boat Flotilla in May 1942.[29] 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.[30]

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 patrolling Short Sunderland found U-559, the aircraft summoned five destroyers able to maintain contact while dropping 150 depth charges over a period of 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.[39]

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 (Dolphin); while U-77, U-205, U-331, U-431, U-561 and U-660 assembled around Algiers as Gruppe Hai (Shark). Five U-boats were sunk opposing the invasion.[39]


Covering the retreat from Tunisia through Sicily

Allied armies advancing through North Africa and Sicily constructed a system of airfields increasing the frequency of U-boat detection by aircraft. The 29th flotilla focused on western Mediterranean convoys supplying Allied troops, but three U-boats were based at Salamis to maintain an eastern Mediterranean patrol presence requiring distribution of Allied ASW efforts. On 1 August 1943 the 29th Flotilla shifted its headquarters from La Spezia to Toulon where it could use the former French naval base for patrols in the western Mediterranean.[52]


After the Italian armistice

As Allied escort forces in the Mediterranean became more numerous, the tactic of hunting a detected U-boat to exhaustion was given the name Swamp and used with increasing frequency. U-boats launched G7es torpedoes with passive homing against destroyers, but were unable to cope with a team of escorts. U-boats remaining in port were subjected to USAAF air raids from newly constructed airfields. Surviving 'U-boats at Toulon were scuttled when Operation Dragoon, (the invasion of southern France), closed the 29th Flotilla base on 15 August 1944. Three U-boats remained at Salamis until Allied forces reached them on 19 September 1944.[56]


Success and failure

HMS Barham explodes as her 15 inch magazine ignites, 25 November 1941.

The Germans sank 95 allied merchant ships totalling 449,206 tons and 24 Royal Navy warships including two carriers, one battleship, four cruisers and 12 destroyers at the cost of 62 U-boats. Noteworthy successes were the sinking of HMS Barham, Ark Royal, Eagle and Penelope.

U-boats sunk by Allied submarines

Four U-boats were sunk by Allied submarines in the Mediterranean.

See also



  1. Paterson, Lawrence - U-Boats in the Mediterranean 1941-1944, 2007, Chatham Publishing, ISBN 9781861762900, pp. 19 and 182.
  3. Paterson, 11th photo caption, between pages 74 and 75
  4. Paterson, p. 6
  5. Paterson, pp. 19 and 182.
  7. Paterson, p. 20
  8. Paterson, 23rd photo caption between pages 74 and 75
  9. "23rd Flotilla". Guðmundur Helgason. Retrieved 2012-06-20.
  10. 1 2 3 4 Blair(1996)pp.395-404
  11. 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 Blair(1996)pp.735&736
  12. 1 2 3 "Ships hit by U-559". Guðmundur Helgason. Retrieved 2012-06-20.
  13. 1 2 3 "Ships hit by U-97". Guðmundur Helgason. Retrieved 2012-06-20.
  14. Blair(1996)pp.399&736
  15. 1 2 Blair(1996)pp.403&735-736
  16. Blair(1996)pp.396-397&736
  17. 1 2 3 "Ships hit by U-431". Guðmundur Helgason. Retrieved 2012-06-20.
  18. Blair(1996)pp.400&736
  19. "Ships hit by U-557". Guðmundur Helgason. Retrieved 2012-06-20.
  20. 1 2 3 "Ships hit by U-562". Guðmundur Helgason. Retrieved 2012-06-20.
  21. 1 2 "Ships hit by U-652". Guðmundur Helgason. Retrieved 2012-06-20.
  22. 1 2 3 4 5 "Ships hit by U-453". Guðmundur Helgason. Retrieved 2012-06-20.
  23. Blair(1996)pp.403&716-719
  24. Taylor(1966)p.124
  25. "Ships hit by U-568". Guðmundur Helgason. Retrieved 2012-06-20.
  26. 1 2 3 "Ships hit by U-77". Guðmundur Helgason. Retrieved 2012-06-20.
  27. "Ships hit by U-573". Guðmundur Helgason. Retrieved 2012-06-20.
  28. 1 2 3 Taylor(1966)p.132
  29. "29th Flotilla". Guðmundur Helgason. Retrieved 2012-06-20.
  30. 1 2 3 4 5 6 7 8 9 Blair(1996)pp.645-654
  31. 1 2 3 4 "Ships hit by U-81". Guðmundur Helgason. Retrieved 2012-06-20.
  32. "Ships hit by U-83". Guðmundur Helgason. Retrieved 2012-06-20.
  33. Blair(1996)pp.553-554
  34. Taylor(1966)p.116
  35. "Ships hit by U-205". Guðmundur Helgason. Retrieved 2012-06-20.
  36. 1 2 3 "Ships hit by U-375". Guðmundur Helgason. Retrieved 2012-06-20.
  37. 1 2 "Ships hit by U-561". Guðmundur Helgason. Retrieved 2012-06-20.
  38. 1 2 3 "Ships hit by U-565". Guðmundur Helgason. Retrieved 2012-06-20.
  39. 1 2 3 4 5 6 7 Blair(1998)pp.81-103
  40. 1 2 3 "Ships hit by U-73". Guðmundur Helgason. Retrieved 2012-06-20.
  41. 1 2 3 4 5 6 7 8 9 10 11 12 Blair(1998)pp.208-217
  42. 1 2 3 "Ships hit by U-371". Guðmundur Helgason. Retrieved 2012-06-20.
  43. 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 Blair(1998)pp.735-751
  44. 1 2 3 "Ships hit by U-593". Guðmundur Helgason. Retrieved 2012-06-21.
  45. 1 2 "Ships hit by U-617". Guðmundur Helgason. Retrieved 2012-06-21.
  46. 1 2 3 "Ships hit by U-407". Guðmundur Helgason. Retrieved 2012-06-21.
  47. 1 2 3 "Ships hit by U-596". Guðmundur Helgason. Retrieved 2012-06-21.
  48. 1 2 "Ships hit by U-755". Guðmundur Helgason. Retrieved 2012-06-21.
  49. 1 2 "Ships hit by U-380". Guðmundur Helgason. Retrieved 2012-06-21.
  50. "Ships hit by U-443". Guðmundur Helgason. Retrieved 2012-06-21.
  51. "Ships hit by U-602". Guðmundur Helgason. Retrieved 2012-06-21.
  52. Blair(1998)pp.216-217&412
  53. 1 2 3 4 5 Blair(1998)pp.375-381
  54. "Ships hit by U-414". Guðmundur Helgason. Retrieved 2012-06-21.
  55. 1 2 "Ships hit by U-410". Guðmundur Helgason. Retrieved 2012-06-21.
  56. 1 2 3 4 5 6 7 8 9 Blair(1998)pp.518-526
  57. 1 2 3 Blair(1998)pp.455-458
  58. Taylor(1966)p.125
  59. "Ships hit by U-616". Guðmundur Helgason. Retrieved 2012-06-21.
  60. 1 2 Blair(1998)pp.411-414
  61. "Ships hit by U-223". Guðmundur Helgason. Retrieved 2012-06-21.
  62. 1 2 3 4 5 6 7 8 Blair(1998)pp.526&735-751
  63. "Ships hit by U-230". Guðmundur Helgason. Retrieved 2012-06-21.
  64. Taylor p.119
  65. "Ships hit by U-952". Guðmundur Helgason. Retrieved 2012-06-21.
  66. 1 2 Blair(1998)pp.521&735-751
  67. "Ships hit by U-969". Guðmundur Helgason. Retrieved 2012-06-21.
  68. "Ships hit by U-967". Guðmundur Helgason. Retrieved 2012-06-21.
  69. Taylor p.142
  70. Taylor p.127
  71. Blair(1998)pp.525-526&735-751
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