The only direct military co-operation between Germany and Japan in World War II took place at sea, principally with submarines. Apart from the limited transfer of VIPs, technicians, strategic materials and new weapons the two Axis submarine fleets co-operated mainly in sinking Allied shipping on the Indian Ocean trade routes. Because these were thought to be easy prey by comparison with the Atlantic, German U-boats were dispatched to the Far East from late 1942 in large numbers. In 1943 and 1944 they sank double the tonnage destroyed by Japanese submarines. Overall, Germany’s tally surpassed Japan’s both in terms of total tonnage and ships sunk, but it was a poor return for the U-boats lost and the resources diverted.

Rather unknown is the fact that during World War I the National Indian Movement had asked the German Imperial Navy to send U-boats into the Indian Ocean. But their range or fuel capacity at that time was insufficient so the idea fell through.

During World War II, U-boats got the chance to operate in the Indian Ocean. Grand Admiral Karl Doenitz (C-in-C submarines) disposed of large U-boats with increased range capable of remaining on station in this far-distant ocean. Doenitz planned the first attack on the South African trade routes to take place during one autumn of 1941 but he cancelled the operation after the destruction of the Armed Merchant Raider Atlantis by HMS Devonshire on 22 November 1941 and of the loss of the supply ship Python on 1 December 1941 which was deliberately scuttled when another Royal Navy cruiser, Dorsetshire, appeared on the horizon.

When the United States entered the war after the attack on Pearl Harbor on 7 December 1941 Hitler told the Japanese ambassador in Berlin, General H. Oshima, that he had recalled the U-boats operating in the Atlantic and that the large boats would now patrol as far down as Cape Town, South Africa. This was meant as a diversionary attack because of the growing efficiency of the antisubmarine measures off the American coast and in the Caribbean.

On 1 August 1942 Doenitz issued the operational order for Gruppe Eisbar (‘Polar Bear Group’) consisting of U68, U156, U172 and U504 — all of the ocean-going, heavily armed IXC type. The U-tanker U459 (Type XIV) was to accompany the group and refuel it. On 7 October the U-boats sank their first victim off Cape Town but only U504 operated off Durban at the end of October. She sank five ships totalling 28,980 tons and damaged one of 7,176 tons. U159 cruised south of Port Elizabeth and scored hits on two ships (12,305 tons) sinking them.

The next U-boat offensive in the western Indian Ocean took place during November and December when U177, U178, U179 and U181, ‘U-cruisers’ (Type IXD2) with a radius of action of 23,700 nautical miles, raided the east coast of South Africa, off Lourenco Marques and off Port Louis in Mauritius Island. At the end of December the U-boats has expended most of their torpedoes and returned for home, arriving in France during January 1943. The boats stayed in those waters for about four months and had sunk 24 ships, totalling 126,535 tons. Thanks to the German submarine reinforcement, November 1942 was the second worst month of the war for Allied shipping in the Indian Ocean, but U179 was sunk by depth-charges on 8 October. The destroyers Nizam, Foxhound and Active found her 60 miles west of Dassan Island (north of Cape Town).

The destroyers had just collected survivors from the British City of Athens which U179 had torpedoed when Active obtained a radar contact at 2328. Shortly after, a large U-boat was sighted on the surface and Active increased her speed to 25 knots, illuminated the U-boat by searchlight and opened fire. U179 crash-dived but Active dropped 10 depth charges which burst all around the submarine. She was blown to the surface and disappeared, never to be seen again.

The next group of U-boats sent to the Cape waters and Indian Ocean was called Seehund (‘Seal’) and consisted of U160, U506, U509, and U516 all of the IXC class. Though these boats were classified as large ones, only U186 was a Type IXD2 like those of the previous group. The most successful Seehund commanding officer was Kapitänleutnant (Lieutenant) Lassen of U160. He sank his first victim in the South Atlantic and on 28 February 1943 rounded the Cape, approaching Durban. Next day he sighted his first ship in the Indian Ocean but could not pursue. On the following two days he sighted a convoy but could not press home an attack. He then gave up his attempts and left for Port Shepstone (south of Durban). But at 1400 on 3 March he got his chance. U160 met a southbound convoy and ran along on a parallel course. Lassen counted eight cargo ships, two tankers, a corvette (Nigella) and three armed trawlers. Though he lost contact at dusk, Lassen could easily overtake the 8-knot convoy, DN21. The night was dark and cloudy so he could make an attack on the surface. 0160 penetrated between the two lines of ships and at 2322 fired three tubes. The American Harvey W. Scott (7,176 tons) and the British Nirpura (5,961 tons) were hit and went down; the Dutch tanker Tibia (10,356 tons) was damaged.

Now, confusion reigned within the convoy. The sinking Harvey W. Scott switched on her upper deck lights; one of the trawlers switched on her searchlight and picked up survivors. Nigella fired starshells and a freighter used tracer, all to the comfort of Lassen who retired to press home his second attack. At 0110 U160 fired two torpedoes and Lassen believed he had sunk two ships. But this time there was only one hit on the British Empire Mahseer (5,087 tons) which went down immediately.

It was enough to break up the convoy. Lassen pursued three large cargo vessels, fired two more torpedoes at 0313 but all missed. At 0346 U160 closed the scattered convoy again and fired two torpedoes, sinking the British Marietta (7,628 tons) and damaging the British Sheaf Crown (4,868 tons). Lassen fired another torpedo 90 minutes later which missed. Then U160 dived to avoid the corvette Nigella which came straight at her. At dawn on 4 March Lassen abandoned the pursuit. During March and April, Lassen sank two more ships so the he is credited with sinking six ships of 38,014 tons and damaging two of 15,224 tons. The official comment on U160′s virtual annihilation of Convoy DN21 read: ‘An operation brilliantly executed by a proven captain showing tactical ability, correct appreciation, perseverance, energy and offensive spirit.’

The U-boats of Gruppe Seehund arrived in France during 3-11 May 1943. Only the big 0182 did not return. She fell victim to the US destroyer Mackenzie on 16 May, NE of Madeira having sunk just one cargo ship. In German U-boat HQ the operation as a whole was assessed as disappointing because of the adverse anti-submarine conditions which had changed considerably even in those remote waters. The best individual result achieved was by an independent Italian submarine, Leonardo Da Vinci, which sank four ships totalling 29,829 tons in the Indian Ocean during April, besides sinking two ships (29,145 tons) in the South Atlantic. Leonardo Da Vinci, during 93 days at sea, was thus credited with six ships totalling 58,974 tons, the sole positive Italian contribution to the Axis submarine effort in the Indian Ocean.

Another strange interloper during the operations of ‘Group Seal’ was U180. The German Naval High Command had arranged with the Japanese Navy for an exchange of equipment and personnel at a rendezvous in the Indian Ocean about 600 miles SE of Durban. U180 would carry ammunition, blueprints of special weapons and the Indian nationalist Subhas Chandra Bose along with his aide Dr. Habid Hasan. These two were needed in Burma to organize an Indian National Army from Indian POWs. The Japanese I-29 would hand over a cargo of gold, quinine, torpedoes and two Japanese naval engineers to study recent U-boat types and training. U180 left Kiel on 9 February 1943 and met I-29 on 23 April south of Madagascar. The transfer of the equipment and personnel was completed on 27 April when both the submarines parted company. 0180, after sinking one cargo vessel in the Indian Ocean, reached Bordeaux on 3 July. I-29 herself became the third and last Japanese submarine to reach German bases in France, with a special cargo, after leaving Malaya in November 1943.

The next wave of U-boats to operate off Cape Town and in the Indian Ocean consisted of seven U-cruisers: U177, U178, and U181 from Bordeaux, U195, U196, U197 and U198 left Kiel. From the beginning of May the U-boats entered the Indian Ocean to operate in the Mozambique Channel south and east of Madagascar as well as off Mauritius. On 21 June six of the seven U-boats, except U195, were south of Mauritius. Their orders were not to attack ships except large troop transports and to keep wireless silence. Those U-boats not taking in fuel should patrol the approaches to Durban.

These operations lasted for over a month but only sent 60,000 tons of shipping to the bottom. It was evident that anti-submarine measures had considerably improved and that the Cape area was of less importance to the British than previously. No wonder the U-boat captains were disappointed and became irritable. Added to their problems was the poor quality of the food and the inefficiency of the tanker/supply ship Charlotte Schliemann.

At that time another submarine cruised west of the Charlotte Schliemann’s six U-boats. This was U511, a Type IXC due to be handed over to the Japanese (in return for rare metals and rubber sent to Germany). On board were Vice Admiral Kichisaburo Nomura (formerly Japan’s ambassador in Washington until Pearl Harbor), the new German ambassador for Japan (Dr. Ernst Woermann) and six other key personnel. U511 reached Kure (Japan) on 7 August where she was re-commissioned by the Japanese as RO.500. This was at the very time that Japan’s I-8 (6 July departure from Malaya) was heading for France with a cargo of quinine and a crew for U1224, destined to become RO.501 but never to reach the Imperial Navy. I-8 docked at Brest on 5 September after a 61-day voyage. She left the same month with 12 German passengers and several hundred tons of strategic materials (including MGs, torpedo machinery and deck-watches). After only one air attack and endless gales she reached Singapore in December. Later I-8 got to Japan, a round trip of 30,000 miles.

By mid-August 1943 most of the U-boats were on their way home. The second phase of the operation was more successful; 22 ships were destroyed but these sinkings cost U197 which was sunk SW of Madagascar on 20 August after several attacks by RAF Catalina flying-boats of 259 and 265 Squadrons. During October U198, U177, U181 and U196 reached Bordeaux again. U195 had already returned home during June because her diesels had caused a lot of trouble.

During their four-month cruise these seven U-boats sank 31 ships totalling 168,244 tons, the most successful boat being U181 with an aggregate of 10 ships (45,331 tons). The submarine’s skipper Korvettenkapitan (Lieutenant Commander) Wolfgang Luth, was the second most successful U-boat captain of World War II. From 1940-43 he sank 44 ships worth 215,147 tons as well as a French submarine. This record earned him the Knight’s Cross with Oak Leaves, Swords and Diamonds — Germany’s highest decoration.

Whereas five U-cruisers reached France safely, Korvettenkapitãn Dommes of U178, had got the order on 22 July to refuel from the Italian submarine Luigi Torelli SE of the Cape of Good Hope. On 7 August Admiral Doenitz asked Dommes whether his boat would be fit for a prolonged patrol in the same area after an overhaul in the Japanese base at Penang, Malaya. Dommes agreed, fueled from Torelli next day and in company with the Italian submarine U178 reached Penang on the 29th.

Why was Dommes sent to Penang? The Battle of the Atlantic had been won by the Royal Navy in May (41 U boats destroyed that month) so that Doenitz had now decided — too late — to send 11 U-boats to the Far East. He believed that in those waters they would have better opportunities and chances and that the anti-submarine measures were not yet fully organized. Until then the U-boat campaign in the western Indian Ocean had not been profitable. The sinkings were uneconomic even if one considered the loss of only two U-boats. The anti-submarine measures in those waters were steadily increasing and because of the Axis surrender in North Africa the Mediterranean was reopened to Allied shipping. It meant that the Cape route lost much of its significance for the Allies.

How did the Japanese react to the German proposals? As early as December 1942 they had offered to place some bases at the disposal of the German Navy, for example Penang and Sebang (in Sumatra). But Doenitz was not in a great hurry to accept the offer as far as his U-boats were concerned. Only after the catastrophe in the Atlantic did he take up the offer. But he would soon be disappointed because the Admiralty and Vice-Admiral Max Horton (C-in-C Western Approaches) had anticipated such a diversionary movement of the U-boats and already by mid-1943 the British were building up powerful forces in India. This was why the Japanese requested the Germans to deploy U-boats in the Arabian Sea instead of the east coast of South Africa.

Fifth ‘wave’ — 11 U-boats and two auxiliaries

Doenitz decided to send the Gruppe Monsun (‘Monsoon Group’) into the Indian Ocean where they should harass Allied shipping, and after completing their patrol enter Japanese-held Penang. The group consisted of nine Type IXC boats and two IXD-2. For refuelling near the equator there was the U-tanker U462. The supply ship Brake would act as a depot ship in the Indian Ocean.

The U-boats sailed from France and Germany between 11 June and 8 July and their captains were ordered to operate in the Arabian Sea and then to proceed to Penang. Right from the beginning the ‘Monsoon Group’ met disaster. On 24 June U200 was sunk SW of Iceland by an American Catalina; on 8 July U514 fell victim to RAF Coastal Command’s 224 Squadron in the Bay of Biscay; on 12 July U506 was sunk by US planes west of Vigo; three days later U509 was sunk by aircraft of the US escort-carrier Santee NW of Madeira when she was looking for the U-tanker U462 which had been destroyed by Santee’s planes west of the Azores; on the 30th the group’s own tender was sunk by 502 Squadron, RAF, NW of Cape Ortegal (Spain) and on 27 August U847 was destroyed by three planes of the US escort-carrier Card in mid-Atlantic. Five of the 11 U-boats proceeding to the Far East and their U-tanker had been finished off before even crossing the equator.

The fuel situation of the U-boats was now so critical that U516 was ordered to supply U532 and U533 from her own fuel and then to return to France. The two boats and the other survivors (U168, U183, U188) got round the Cape of Good Hope and joined the supply ship Brake about 450 miles south of Mauritius where they refuelled during 8-14 September Doenitz was now looking forward to a surprise blow from his U-boats in the Arabian Sea but Japanese submarine operations in these waters had already alerted Eastern Fleet HQ so that convoys were being introduced and strong air and sea patrols covered the endangered routes to Durban, Mombasa, Aden, Bombay and Colombo.

After having refuelled from the supply ship Brake the boats of Gruppe Monsun proceeded to their assigned patrol stations; U168 to the Indian coast south of Bombay, U532 to the mid-ocean Chagos Archipelago and Ceylon, U183 and U533 to the Seychelles-Gulf of Aden area and finally U188 to the southern coast of Arabia. The group was joined by U178 from Penang. The six submarines did not have much success during their patrols which lasted until November. They sank only three ships (20,801 tons) during September and three more (13,015 tons) in October. Group Monsoon then withdrew to Penang, first arrival being U183 on 17 October. But the day before, U533 was lost in the Gulf of Oman to an obsolete RAF Blenheim Mk.V (Bisley) of 244 Squadron. The remaining four units were overhauled in Penang so that only U178, which should have returned to Germany for a refit, prowled the Indian Ocean for the rest of 1943 and sank one ship of 7,244 tons.

Penang was far from being an ideal base for the German Far East U-boats. It had never been a naval base and no trained labor or dockyard facilities were available. The U boat crews could undertake only emergency repairs assisted by shore personnel from the Armed Merchant Raider Thor (lost by fire at Yokohama, Japan, on 30 November 1942). It is not surprising that it took 50-70 days to overhaul a U-boat and prepare her for the next war patrol. As an example of the difficulties, a flashlight or battery could only be got from Bangkok, hundreds of miles distant.

Only one got through

In the autumn of 1943 Doenitz decided once more to send all boats of the large IXD-2 type to the Indian Ocean as soon as they were commissioned. It was the second Monsoon Group but fared even worse than the first after the submarines left their bases in France and Norway. The US Navy had established an airfield on Ascension Island with B24 Liberators and B25 Mitchells available to patrol the mid-Atlantic and out of four U-boats sent only one reached Penang. U848 was destroyed by one of the planes, 290 miles SW of Ascension, on 5 November, U849 on the 25th off the Congo estuary and U850 west of Madeira on 20 December by planes from the US carrier Bogue. Only 0510 (Kapitãnleutnant Eick) a Type IXC type boat, got through. She left Lorient on 3 November and rounded the Cape in January 1944. Though her movements were detected by RDF (Radio Direction Finding) the search for her was not successful. U510 sank five ships (31,220 tons) and damaged one of 9,970 tons during February and March before entering Penang; a notable individual score at this period of the war.

By now torpedoes were running short in the German naval base. U1062 (Type VIIF) left Bergen in Norway on 3 January 1944 with 39 torpedoes (25 as cargo) on board. The three remaining U-boats in Penang (U168, U188 and U532) were meanwhile taking on board important cargoes and preparing for the long and perilous voyage home. They left the base between 4 January and 7 February and were ordered to expend their torpedoes in the Indian Ocean. U188 sank seven ships (42,549 tons), U532 another two and U168 two small vessels.

By RDF fixes the Royal Navy’s Eastern Fleet could locate the supply ship Charlotte Schliemann east of Mauritius. The ship had already refuelled U178 and U510 on 28 January and should now refuel U532. Eastern Fleet guessed that Charlotte Schliemann was still in the area so the cruiser Newcastle, the destroyer Relentless and Catalinas from Mauritius were sent out to find and destroy her. Even the captains of Charlotte Schliemann and U532 decided on 11 February to shift their point of rendezvous to the south, i.e. into mid-ocean, because they would not run the risk of being detected by air patrols. Should planes attack the tanker, U532 would not dive but open fire with her flak guns. After two hours a Catalina was sighted and U532 dived in spite of the promise not to do so. The U-boat surfaced during the night to search for the supply ship but did not find her.

The Catalinas had summoned the destroyer Relentless which opened fire at 0100 the next day and then fired torpedoes at the supply ship, scoring one hit. The crew of Charlotte Schliemann abandoned her and 41 officers and men were taken prisoner. Gradually the Indian Ocean became even less attractive for the U-boats, which sank seven ships in February 1944 and four in March. On 11 March the second and last supply ship, the tanker Brake, met the same fate as Charlotte Schliemann. She was about 1,000 miles SE of Mauritius and refuelling U188, U168 and U532. Again the Royal Navy got RDF fixes on the U-boat concentration, due to the ex-Italian U-boat UIT22 continuously sending radio signals to Brake while on her way to Japan. Eastern Fleet HQ sent out the escort carrier Battler, the cruisers Suffolk and Newcastle as well as the destroyers Roebuck and Quadrant to have a look at the presumed rendezvous. One of the carrier-borne aircraft sighted the tanker and U-boats at 1600 and homed Roebuck to the point. The destroyer opened fire and Brake was then scuttled by her crew. U188 reached Bordeaux on 19 June and U532 Penang on 19 April, together with U1062 which brought the precious torpedoes.

So far Doenitz had committed 42 U-boats to his Indian Ocean campaign, 12 had been lost to planes and ships, 23 had made the round trip successfully but only six were at this time operational in the Far East; U168, U183, U532, U510, UIT24 and UIT25. But it was still believed that the Indian Ocean had a high concentration of Allied shipping, ignoring the fact that even in that sea most ships sailed in convoy and not independently. Doenitz should have known this and that his U-boats had no chance of penetrating the convoy escorts and firing their torpedoes. New submarine groups were sent out during 1944 but to reduce the risk of detection from the air the U-boats sailed independently, most of them being sunk.

Of the first six U-boats U177, U1059, UIT22 and U851 were sunk by air attacks before rounding the Cape. Only three got through to the Indian Ocean. Then fate caught up with U852, a new IXD-2 type cruiser which had left Kiel on 18 January 1944 under Kapitanleutnant Eck, the successful skipper of U50. On 13 March, Eck had sunk the Greek freighter Peleus of 4,695 tons in mid-Atlantic, machine-gunned the survivors on the rafts and hurled hand-grenades at them. Four men were still alive when U852 left the scene and three of them were rescued after 35 days. U852 was caught in the Arabian Sea on 3 May and heavily damaged by RAF planes (8 and 621 Squadrons) SE of Socotra Island, going aground off Somalia. Kapitanleutnant Eck, the medical officer, the officer of the watch and the rest of the crew were brought to England where the U852 atrocity was investigated. Only after the war were these three U-boat men brought to trial in Hamburg and sentenced to death. They were executed by a British firing squad on 30 November 1945.

The next nine U-boats followed between March and May 1944. Lost to US escort-carrier groups were U860 and the U-tanker U490. All other boats reached the Indian Ocean but the pickings were few and far between; three ships during June, four in July and eight in August. During this period U168, U183, U510 and U532 were undergoing repair and overhaul at Penang. While U198 sank two large British ships near Cape Delgado and Dar-es-Salaam in the first week of August, three warships of 3rd Escort Group sailed from Durban in search of her. The escort carriers Begum and Shah, with four frigates, joined in the hunt. Finally on 10 August an Avenger aircraft from Shah sighted U198 about 600 miles east of Mombasa. Next day another plane from the carrier sighted the U-boat again about 80 miles NW of the Seychelles. The aircraft dropped depth charges as U198 crash-dived. The U-boat came to the surface again and opened fire with her flak guns. U198 evaded the plane but later a Catalina sighted her farther north. At dawn on 12 August the British frigates and the Royal Indian Navy sloop Godavari closed the position. The latter ship and the frigates Findhorn (Royal Canadian Navy) and Parret dropped depth-charges and after the first salvo heavy explosions were heard under water and large oil patches came to the surface. That was the end of U198.

The last U-boats to reach the Indian Ocean were the Type IXD-2s U861 and U862. Two more U-boats, U863 and U871, were sunk in the Atlantic during their attempts in September to reach the Far East. After the Allied invasion of France, U180 and U219 were converted to transports and sailed from Bordeaux on 20 August. Two days later U180 struck a mine on leaving the Gironde, but U195 reached the Indian Ocean. Though U862 was attacked on 20 August off the Comore Islands in the Mozambique Channel, by a Catalina (which was shot down) and hunted by an escort carrier group, she entered Penang on 9 September. U861 reached Penang on the 22nd.

During August and September U859 reappeared in the Gulf of Aden and sank two 7,000-ton ships. But in a well-laid ambush the British submarine Trenchant torpedoed her on 23 September at the very doorstep of Penang. Ironically, the two boats had left their home ports on the same day in the spring.

Already on 14 February UIT23 had been sunk by Tallyho and on 17 July the Japanese I-166 succumbed to Telemachus. The Penang trap seemed to be closed by British submarines based at Trincomalee, Ceylon. Doenitz decided to transfer the base to Batavia, in Java. In Penang everything including torpedoes was short and the Japanese as usual unhelpful, but now more unfriendly as Germany’s fortunes declined. The still-operational U-boats were loaded with strategic raw materials such as tin, rubber, wolfram, opium and ordered back to Germany.

U168 left Batavia on 4 October and was sunk the next day by the Dutch submarine Zwaardvisch. Farthest east of all the U-boats to perish she had accounted for just one ship. U181 left Batavia on 19th and sank the 10,198-ton American tanker Fort Lee east of Mauritius. Then engine trouble forced her back to Batavia. The US submarine Flounder caught U537 off Bali on 9 November. U196 sailed on the 11th and was lost on the Sunda Strait. U510 returned to Europe, as well as U843. U862 operated off Fremantle as one of the last U-boats in the Far East during February 1945 and sank two sizeable ships. U510 made a second attempt to reach Germany but being short of fuel had to surrender at St. Nazaire and served in the French Navy until 1958. U195 suffered engine trouble and had to return to Batavia. U183 was torpedoed by the US submarine Besugo in the Java Sea on 23 April 1945.

Though the tables were turned for Germany, two further attempts were made to get through to the Indian Ocean. U864 left Bergen (Norway) on 5 February 1945 but was sunk a short way out by yet another target hungry Allied submarine, HMS Venturer. U234 left Europe with two important Japanese submarine designers on board. She surrendered on 16 May in Portsmouth, US, where the Japanese committed suicide.

The remaining U-boats in the Far East were U181, U195, U219 and U862 as well as the transports UIT24 and UIT25 which were seized by the Japanese in May and commissioned by the Imperial Navy, merely to surrender ingloriously three months later. So ended the U-boat operations in the Indian Ocean and Far East: ‘Misconceived, misdirected, and tragically wasteful in spite of devotion to duty, the valiant efforts, sacrifices, and success of the Far East cadre’.