This was a British combined air and sea undertaking in the Indian Ocean to locate and destroy the 7,747-ton German oiler and supply vessel Charlotte Schliemann (8/13 February 1944).
Built as the Norwegian Karl Knudsen and sold to a German operator in 1939, this important German support vessel had reached Las Palmas in the Spanish Canary islands group on 2 September 1939 with 10,800 tons of oil fuel, which had been loaded at Aruba in the Dutch West Indies. The German ship remained at Las Palmas until a time early in 1942, and in this period the ship apparently supplied fuel to only one vessel, an Italian submarine. On 24 February 1942 Charlotte Schliemann departed the Canary islands on a mission to supply the German raiders Stier (otherwise HSK6 and to the British 'Raider J') and Michel (otherwise HSK9 and to the British 'Raider H'), and between April and August she rendezvoused on three occasions with each of the raiders in the South Atlantic.
On 4 June 1942 Stier sank the 4,986-ton British Gemstone and two days later the 10,170-ton Panamanian tanker Stanvac Calcutta, and the raider transferred the prisoners from these two vessels to Charlotte Schliemann. On 19 April Michel sank the 7,468-ton British tanker Patella carrying nearly 10,000 tons of fuel oil from Trinidad to Cape Town, and four days later sank the 8,684-ton US tanker Connecticut, also bound for Cape Town. On 20 May Michel sank the 4,245-ton Norwegian freighter Kattegat with gun fire, and on 6 June this raiderís small torpedo boat LS 4 (Esau) made a night attack on the 7,176-ton US freighter George Clymer, which Michelís captain believed had been sunk. But the US ship had made a sighting and distress signal which was heard by the headquarters of the British Commander-in-Chief, South Atlantic (located at Freetown, Sierra Leone), who detached the armed merchant cruiser Alcantara from her task of escorting the WS.19 convoy. On 7 June Alcantara found George Clymer still afloat, rescued her crew, and sank the badly damaged American ship on 12 June.
Five days later Michel sank the 5,186-ton British freighter Lylepark to the south of Ascension island. Michel then made rendezvous with Charlotte Schliemann and the converted minelayer Doggerbank, and offloaded her prisoners. (Doggerbank was formerly the British ship Speybank, which had been captured in the Indian Ocean early in 1941 by another German raider, Atlantis (otherwise HSK2 and known top the British as 'Raider C'), which sent her with a prize crew to Bordeaux, where she was converted into an auxiliary minelayer.)
The three German ships remained in company for a week before Michel detached to operate east of Ascension island in the area in which, on 15 July she sank the 8,006-ton British passenger and cargo ship Gloucester Castle with gun fire and a torpedo, 90 lives being lost. On the following day the raider sank the 7,893-ton US tanker William F. Humphrey returning to Trinidad in ballast, and the torpedo boat damaged the 7,984-ton Norwegian tanker Aramis in a night attack. Aramis made a raider report and did her best to escape, but after a one-day pursuit Michel caught and sank her. The raider than steamed south and met Stier and then Charlotte Schliemann, the latter taking on board all of Michelís prisoners. When she supplied Michel on 21 June 1942, Doggerbank also transferred most of her remaining supplies to Charlotte Schliemann and took on board 177 merchant seaman captured by raiders.
Doggerbank then steamed first to Batavia in the Japanese-occupied Dutch East Indies, and thence Japan,where she was adapted as blockade runner: her career ended on 3 March 1943 off the Canary islands when U-43 sighted her, misidentified her as a British vessel and sank her.
On 27 August 1942 Charlotte Schliemann refuelled Stier for the last time and than headed for Japan. In June 1943 Charlotte Schliemann was used to refuel at least seven U-boats in the area to the south-east of Madagascar. These boats had been operating in the waters off the Cape of Good Hope, and after refuelling moved north and north-east to search for Allied shipping in Mozambique Channel and steaming between the Cape of Good Hope and India or Ceylon.
In January and February 1944 there were serious delays in the movements of Allied shipping in the Indian Ocean, and for this the primary reason was the inadequacy of the regionís port facilities rather than the time required to marshal and convoy merchant shipping. Even so, Admiral Sir James Somerville, commanding the Eastern Fleet, relaxed some of the protective measures, in line with the wishes of the Admiralty, and for a time this appeared to have eased matters.
Then, during the last 10 days of January 1944, six independently routed ships were sunk, and the total losses for the month were eight ships of 56,213 tons, which was the highest in any theatre of war during the course of that month. Four U-boats were working in the Gulf of Aden and north of the Maldive islands, and it was these which inflicted most of the damage. A search was made to catch Charlotte Schliemann, which was thought to be waiting in an area to the south of Mauritius to refuel the U-boats. The vessel had, in fact, not yet arrived on station at the expected rendezvous.
The highly successful career of this important German naval support vessel came to an end in February, however, after she had been sighted and reported by a Consolidated Catalina flying boat operating from the island of Mauritius. The oiler was then intercepted and sunk on 9 February by the destroyer Relentless, which returned to base on 13 February. As Charlotte Schliemann had refuelled only two U-boats before she was destroyed, the patrols of the other boats were necessarily shortened. Early in February Somerville reintroduced the convoy concept to the routes on which, at the behest of the Admiralty, he had recently suspended it. Some time inevitably passed before the reintroduced system could become effective, and most of the 10 ships (64,169 tons) sunk during the month were still sailing independently.