Mediterranean U-boat campaign of World War II

The Kriegsmarine had acquired some knowledge of the area. Dönitz was an officer aboard 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. , and 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-25s 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. 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. • passed Gibraltar on 21 September 1941. • passed Gibraltar on 26 September 1941, • passed Gibraltar on 27 September 1941, • passed Gibraltar on 30 September, destroyed a 372-ton British landing craft on 10 October, and sank on 25 November 1941. • 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 on 28 December 1941. • passed Gibraltar on 5 October, damaged on 21 October, and was sunk on 23 December 1941 by Royal Navy destroyers. • was sunk near Gibraltar on 16 November 1941 by . • passed Gibraltar on 26 November, sank the 4,032-ton Fjord on 2 December, then sank on 15 December, and was sunk on 16 December 1941 by the . • passed Gibraltar on 27 November 1941 • was torpedoed by the Dutch submarine O 21 while passing Gibraltar on 28 November 1941. • passed Gibraltar on 8 December 1941. • sank the trawler HMS Lady Shirley and the patrol yacht HMS Rosabelle while passing Gibraltar on 10 December 1941 and was torpedoed by on 12 January 1942. • passed Gibraltar on 10 December 1941 • passed Gibraltar on 15 December 1941. • passed Gibraltar on 18 December 1941. • was sunk by Fairey Swordfish from 812 Naval Air Squadron while passing Gibraltar on 21 December 1941. • passed Gibraltar on 21 December 1941. • passed Gibraltar on 23 December 1941 and was sunk by aircraft on 9 January 1942. • passed Gibraltar on 14 January. • 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. • sank on 11 August 1942. • 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. • 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. and sank after striking a mine off Salamis on 12 March 1942. • sank the 2,623-ton Slavol on 26 March 1942, and sank on 16 June 1942. • shelled the Beirut electric power station in April 1942. • 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. • damaged the 3,359-ton Adinda on 24 July 1942. • was hunted to exhaustion on 28 May 1942. • was interned in Spain following bomb damage on 1 May 1942. • sank on 20 March 1942, sank 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. • sank the 18-ton Mahrous on 20 October 1942, damaged HMS Stork on 12 November, and sank the 6,699-ton Empire Banner and the 7,043-ton Empire Webster of convoy KMS 8 on 7 February. U-77 damaged the 5,222-ton Hadleigh and the 5,229-ton Merchant Prince of convoy ET 14 on 16 March • sank the 2,012-ton Garlinge on 10 November 1942 and the 6,487-ton Maron on 13 November. U-81 damaged the 6,671-ton Saroena on 10 February 1943 and sank sailing ships Al Kasbanah, Dolphin, Husni, and Sabah el Kheir on 11 February. U-81 sank the 244-ton Bourghieh and sailing ship Mawahab Allah on 20 March 1943, and sailing ship Rousdi on 28 March. • damaged on 1 December 1942. and was sunk off Oran on 14 November 1942 by a Lockheed Hudson of No. 233 Squadron RAF. • passed Gibraltar on 11 October • passed Gibraltar on 9 November 1942 • passed Gibraltar on 9 November • passed Gibraltar on 9 November 1942 • passed Gibraltar on 11 November • passed Gibraltar on 5 December 1942, before being sunk by destroyers on 23 February 1943. • passed Gibraltar on 9 December 1942 and was torpedoed by on 20 January 1943. • passed Gibraltar on 9 January 1943 and was sunk on 13 January by . ==Axis defeat in Tunisia==

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, forcing the Allies to disperse their 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. • sank the 1,598-ton Brinkburn of convoy TE 22 on 21 June, and damaged the 8,299-ton Abbeydale of convoy XTG 2 on 27 June 1943. • sank the 1,162-ton Merope on 27 April, damaged the Liberty ship Matthew Maury and the 6,561-ton Gulfprince of convoy ET 22A on 10 July 1943, and sank the 6,004-ton Contractor of convoy GTX 5 on 7 August 1943. before being sunk on 25 May 1943 by . • was sunk off Gibraltar on 7 May 1943 by Lockheed Hudsons of No. 233 Squadron RAF. and was sunk on 12 July 1943 by . ==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. • damaged the Liberty ship John S. Copley of convoy GUS 24 • sank the 2,887-ton Empire Dunstan on 18 November 1943 • sank Liberty ship Christian Michelsen of convoy UGS 17 on 26 September 1943. U-410 then sank Fort ship Fort Howe and damaged 3722-ton Empire Commerce of convoy MKS 26 on 1 October and sank Fort ship Fort Saint Nicolas on 15 February 1944, on 18 February, and LST-348 on 20 February • sank Liberty ship William W. Gerhard of convoy NSS 3 on 21 September 1943, on 25 September, 4531-ton Mont Viso of convoy KMS 30 on 3 November, and and of convoy KMS 34 with G7es torpedoes on 12 December with G7es torpedoes before being hunted to exhaustion by convoy escorts on 14 May 1944. Replacements • passed Gibraltar on 26 September 1943, with a G7es torpedo while being hunted to exhaustion on 29 March 1944. • passed Gibraltar on 5 December 1943, before being scuttled at Toulon on 21 August 1944. • passed Gibraltar on 3 January 1944, sank Liberty ship William B. Woods on 10 March and was destroyed in Toulon by USAAF raids on 5 July and 6 August 1944. • passed Gibraltar on 3 February 1944, damaged Liberty ships George Cleeve and Peter Skene Ogden of convoy GUS 31 on 22 February, and was destroyed in Toulon by USAAF raids on 5 July and 6 August 1944. and was scuttled at Toulon on 11 August 1944. • passed Gibraltar on 20 March 1944 and was destroyed by a 29 April 1944 USAAF raid on Toulon. • passed Gibraltar on 31 March 1944 and was destroyed in Toulon by USAAF raids on 5 July and 6 August 1944. ==Success and failure==

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 , , and . U-boats sunk by Allied submarines Four U-boats were sunk by Allied submarines in the Mediterranean: • was sunk on 28 November 1941 in the western Mediterranean, south-west of Almería, in position by torpedoes from the Dutch submarine HrMs O 21. 35 crewmembers died and 12 survived. • was sunk on 21 January 1943 in the Mediterranean, west of Bonifacio, in position by torpedoes from the British submarine . 45 crewmembers died and 1 survived. • was sunk on 21 May 1943 in the western Mediterranean south of Toulon, in position by torpedoes from the British submarine . 20 crewmembers died and 28 survived. • was sunk on 12 January 1942 in the western Mediterranean, east of Cape Spartivento, in position , by torpedoes from the British submarine . Only one crewmember out of 45 survived. ==See also==