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German Submarines in the Pacific Ocean? The Forgotten Monsun Gruppe Wolfpack

On October 14th, 1939, during a raid on Scapa Flow by the U-47, a German submarine, the HMS Royal Oak was torpedoed and sunk. The captain of the German submarine, Günther Prien, was awarded the Knight’s Cross of the Iron Cross. Due to the success of this secret raid, the German Kriegsmarine realised the potential of U-boats and would eventually ramp up their production. Now, the Battle of the Atlantic is incredibly well-documented. For a good reason, by the way, as it is the most extended uninterrupted military campaign of the war. In total, between September 1939 and May 1945, the Germans lost 783 submarines, and the Italians lost 17. 

Something that is covered far less extensively, and isn’t necessarily as bloody, but is interesting nonetheless, is the special flotilla of U-boats the Kriegsmarine sent to the Indian Ocean and Pacific war theatre. This squadron, the so-called Monsun Gruppe, had to disrupt Allied shipping transports and maintain contact with the Japanese, the German allies on the other side of the world. Their base was located in Penang, on the Northwest Coast of Peninsular Malaya. Perhaps most interesting of all: although Japan and Germany were officially allied during the war, this was the only time both powers intensively collaborated.

Early Maritime Connections

During the initial stages of the war, there was some talk among Kriegsmarine admirals to send a flotilla of U-boats to the Indian Ocean. Although it would be an addition to have manpower there and disrupt Allied supply lines, nobody considered it a feasible mission. U-boats were challenging to resupply, the Germans didn’t exactly have an abundance of them, and there was an intensifying war waging in the North Atlantic Ocean. Because sending a squadron of U-boats to the Indian Ocean suffered so many logistical issues, commanders decided to hold off from doing so.

Erich Raeder (1876-1960)

Although there wasn’t very intensive contact between Japan and Germany, the communication they did have consisted of cargo boats transporting goods between the two powers. Japan suffered from notorious resource problems and a technological disadvantage compared to their main adversary, the United States. Meanwhile, the German war machine required resources available to Japan, such as tungsten, quinine and rubber. Regardless of the occasional cargo shipments, Germany and Japan never managed to establish a stable logistical naval connection. 

Of the 37 cargo ships that started the journey from German ports to Japan, 20 did not return. There was a tremendous risk on the route through the Atlantic Ocean, past the South African Cape of Good Hope, the Indian coastline and the war theatres over there. Following excessive losses, the German Admiral Erich Raeder decided to put to a stop any attempts to establish a naval connection with Japan.

This changed when on January 30th 1943, Admiral Karl Dönitz was appointed as Supreme Commander of the Navy, replacing Erich Raeder. Previously Dönitz was the senior submarine officer of the Kriegsmarine. His appointment could not have come at a better time regarding the plan to send a submarine squadron east and intensify naval relations with the Japanese, which by this point hadn’t really been considered seriously anymore. 

There were several upsides a base near the Pacific theatre would have for the Germans. Due to the losses both on land and sea Germany could benefit from an overseas port and supply line. Not to mention that due to Operation Barbarossa contact with their Japanese allies was hindered even further. And the Pacific theatre wasn’t too hindered by submarine warfare so that the Allied cargo convoys wouldn’t be protected to the degree they were in the Atlantic Ocean. Some surprise strikes by weaponised transport submarines could very well help the German war effort and would undoubtedly do more damage than it would in the Atlantic Ocean.

The Maritime Route (source)

Dönitz considered using submarines for transport to and from Japan, using their stealth to evade Allied squadrons on their way. Initially, this idea was given the green light, but due to heavy losses of submarines in subsequent battles in the North Atlantic Ocean, the plan was put on hold. By this point, the tide of war turned against Germany, both on land as the Germans lost the Battle of Stalingrad by February 1943, but also on the sea, with the Kriegsmarine losing dozens of submarines every month. In turn, German commanders decided it would be foolish to use their valuable submarines for transport. But that is not to say they gave up the plan of using submarines for transport. Instead, they appealed to their Allies, the Italians. According to Dönitz Italian submarines weren’t made for modern warfare anyway. A pretty telling statement about the German-Italian alliance during the war. 

It was during that time Japan requested two German submarines so they could study them and use their design to improve their own submarines. Toying with the idea of using Italian submarines for transport and German submarines to hinder Allied convoys in, and near the Pacific, the Kriegsmarine decided to send two submarines: the U-511 and U-178.

The crew of these submarines were tasked with establishing an operational submarine base on Penang, an island northwest of the Malay Peninsula. Previously the island was used as a seaplane base by the British, but early on in the war the Japanese captured the area and established an operational base for their fleet. 

The RO-500 with Japanese flag

As for the U-511, it set sail to Penang in May 1943. It arrived earlier at Penang than its counterpart, the U-178. It was given to the Japanese to study and inspect its design. It was renamed to RO-500, the photograp above is of the submarine with a Japanese flag on it. As for its crew, it remained in Penang to replenish the ranks of the submarines that would undoubtedly arrive at any time. And they would. Three weeks later, the U-178 arrived. This U-boat had initially been patrolling the Mozambique Channel between Gibraltar and Mozambique. During this mission its commander, Wilhelm Dommes, received orders to sail to Penang, to establish a base there. Once the base was established, Dommes would become the commander of the entire Asian squadron of German U-boats. It was on August 27th they arrived at Penang. And several more U-boats were already on their way. 

The Monsun Gruppe

Although the two U-boats didn’t arrive until August 1943, by June the command of the Kriegsmarine already decided upon increasing the presence of U-boats in Asia. The first batch of 11 U-boats would form the core of the so-called Monsun Gruppe. Its name refers to the Monsoon season, during which the U-boat campaign should start in the region. Yet it was a maritime route full of dangers and hardships for the U-boats. And although all 11 were Type IX submarines, designed for operations far from home, even for them a voyage past the tip of Africa and through the Indian Ocean was a challenge. Among these subs was the U-200, a Type IX D2. Among its crew were several soldiers of the famous Brandenburger division, special sabotage units I have created a separate video about. Their mission was to land in South Africa and sway the Boers to pick up arms against the British. Yet the submarine didn’t come that far, and near the coast of Iceland, it was sunk by depth charges from a British Liberator plane. Eventually, of the 11, only five U-boats ended up reaching the peninsula. The rest were sunk during their voyage.

Mid-ocean replenishment

A pretty telling example of how difficult it was to reach the peninsula and traverse the hostile areas in the ocean, is the example of the replenishment submarines that accompanied the wolfpack. Initially, the U-462, fitted to transport cargo, had a tough time in its attempt to reach the peninsula. It was severely damaged by Mosquito aircraft in the Bay of Biscay. Following repairs, it was attacked near the Spanish coast by a British B-24 Liberator. The repairs from this attack took a month and the submarine wasn’t able to rejoin the wolfpack sailing to the Malayan peninsula. Once repaired in late July, it didn’t have any more luck. A British Halifax bomber definitively sank it. In response to the U-462 not being able to join the wolfpack, the Kriegsmarine sent the replenishment U-boat U-487. In early July this submarine was sunk, by chance, in the central Atlantic by U.S. Avengers and Wildcats before ever reaching the group. 

Right, so only five boats reached the Penang base in November, where the U-178 welcomed them. These five remaining U-boats formed the core of the Monsun Gruppe, but weren’t operational yet. All of them had to be repaired following the nightmarish journey. That brings us to the central problem the Monsun Gruppe faced once they arrived: repairs. The total average downtime of a U-boat upon arrival was 50 days. The German crew weren’t well-versed in Japanese culture, and cooperation wasn’t exactly easy. The Japanese refused to work for white men, for example, so in practice the German crew had to fix their U-boats on their own. The language barrier caused problems as well. One of the funniest anecdotes I came across was when the Germans showed Japanese locals a broken copper screw which they required for a pump. The Japanese started the production of a batch of screws, but once finished they delivered an entire batch of broken-off screws. They had simply recreated the faulty one. 

When the U-boats finally were made operational, their success in combat wasn’t great either. In total they managed to sink six Allied cargo ships and six dhows, a more traditional sailing vessel. Meanwhile, of these subs only two would see the end of the war. All in all, their deployment was insanely costly and barely yielded results.

Sinking of the U-848 on its way to join the Monsun Gruppe

During late 1943 five more submarines started their journey to Penang as an addition to the Monsun Gruppe. Of these five, just one, the U-510 arrived in April 1944. The other four were sunk. Due to limited capacity, as this map perfectly shows, the German U-boats that eventually arrived often used other bases in the region. There were small bases around Jakarta and Surabaya. These too were mainly operated by Japanese shipyard workers, in turn producing the same problems. Of 23 subsequent U-boats that set sail to Penang from the European theatre, only nine made it. As for the Italian submarines, the story isn’t much better. Seven submarines were sent in total. One of them, the Ammiraglio Cagni, learned of the Italian armistice and surrendered at South Africa. Two others disappeared into the ocean, the Bagnolini sunk off the Cape of Good Hope and another managed to reach Penang, but upon its return, it was torpedoed and sunk. The Commandante Cappellini and Torelli did arrive at Penang and served the Germans for as long as the war continued. 

The Comandante Cappellini

End of the War

From early 1944 onwards the Germans focused more on transporting materials from Asia to Germany than missions against Allied cargo convoys. Actually, the only real combat victory in the Pacific theatre of the entire mission was by the U-862, commanded by captain Heinrich Timm. This submarine torpedoed and sank the American SS Robert J Walker. This was the only German U-boat that sank an Allied ship in the Pacific Ocean. There were other successes around the Indian Ocean, however. Aside from the six vessels and six dhows sunk by the initial submarines, in total the submarines that did make it to the Asian bases and were redeployed on a mission, sunk 33 ships. Still, considering the losses, this wasn’t a great victory ratio. As for the transport submarines, it was even worse. Of the 24 merely two safely returned to Europe to deliver quinine and rubber. Four others didn’t turn up until Germany had already surrendered. So you could say the entire endeavour was insanely costly and barely effective for the Germans.

There were several reasons why the Monsun Wolfpack wasn’t a success. The Allies had cracked the enigma code, rendering U-boats far less useless. And the Allies became aware of German submarines in Asia, so they naturally upped the protection of cargo convoys. I already touched upon the problematic repairs and there was a severe shortage of materials which became increasingly worse as the war progressed. And the fact Germany was losing ground in the European theatre rendered a large chunk of the commanders of the Wolfpack guessing what their next action should be. Towards the end of the war the U-boats received the order to return to the Atlantic Ocean and join the war effort there. During their return journey, many of them were picked off by Allied torpedo boats and Allied warplanes. 

When Germany surrendered on May 8th 1945, only six submarines, including crew, were leftover in Asia. The Japanese Imperial Navy took over command, and their war would last for several more months. The German crew that stayed behind and continued training Japanese submarine crews, as they had done for the past months. The Japanese navy now integrated the remaining submarines into their navy. Two Italian-turned-German submarines and four actual U-boats were designated with the I-suffix. Of these, the I-506 wasn’t even used during these months due to a shortage of Japanese crewmen. Two other submarines merely went on short training missions, but saw no combat. The Italian submarines were never used either – so as you can tell, they met a pretty uneventful fate. 

When Japan officially surrendered following the atomic bombing of Hiroshima and Nagasaki, the Japanese scuttled the Italian submarines which at this point were stationed at Kobe. In total, 41 German submarines left for Asia, and only six ended up safely returning to Europe. Even those that safely returned were scuttled following the war because they weren’t deemed seaworthy anymore.  After Japan’s surrender, British soldiers captured and arrested the Germans remaining in Penang. Captain Dommes was released two years later in 1947 and lived until 1990. That goes for most of the crew: most of them didn’t receive any severe punishment. Well, except for one man. 

In early 1944 the Captain of the U-852, Captain Heinz-Wilhelm Eck ran into the Greek ship Peleus. Reasoning he was on a secret mission, he torpedoed the ship and had all merchantmen killed. Following the war he was put on trial, convicted of war crimes and executed. His case was the only case of U-boat personnel convicted of such acts, only to be executed thereafter.

 To summarise I think it’s safe to say that the Monsun Gruppe and German attempts to

establish a submarine base in Malaya was an utter failure. Partly because they were victims of circumstance, but also because it was a mission that faced so many logistical difficulties before it had even started that it’s odd the Kriegsmarine continued with it anyway. 


Worthen, Dennis B. "The national quinine pool: when quinine went to war." Pharmacy in history 38, no. 3 (1996): 143-147.

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