World War II: German Nuclear Transfers to Japan


Figure 1.--.

We know that the Japanese and Germans were cooperating on nuclear weapons because of Magic decrypts. These decrypts described efforts to share military technology and critical materials. The Japanese attached great priority to obtaining enriched uranium. Allied command of the sea severely limited contacts between Axis allies Germany and Japan. Several German and Japanese submarines were involved in this effort because by the time the Japanese requested the uranium, surface transport was no longer possible. Details on most of the submarine transports are hazy. Ee know a cgreat deal aviut the last one--the U-234. This is because the captain surrendered to the Americans who recovered 560 kg of enriched uranium aboard. We do not know if the Germans transg\ferred nuckear technology to Japan. The U-234 was a very large mine-laying U-boat. It had been adapted as an undersea freighter to carry a much larger cargo than a standard U-boat. Germany transferred considerable weapons technology to Japan. Once the War began because of the Royal Navy and later the U.S. Navy's control of the Atlantic this had to be done mostly by U-boat. The U-234 was dispacted to Japan with a cargo of German high-tech equipment (April 1945). The cargo included air defense radars and jet engine equioment as well as German technical experts. In addition there were 80 gold-lined cylinders containing 560 kilograms of uranium oxide marked "For the Japanese Army". There is very limited cargo space even aboard this cargo U-boat. Thus only items of the highest priority would have been loaded. The only pupose for the uranium oxide given the state of Japanese nuclear research would have been a dirty bomb. Also aboard were two Japanese officer--Air Force Colonel Genzo Shosi, an engineer, and Navy Captain Hideo Tomonaga. The U-234 was informed of Hitler's suicide (May 1). Naval Highcommand ordered all German submarines to observe a ceasefire (May 4). The order to surrender was then given (May 8). The captain of the U-234 at this time arrested the Japanese officers who subsequently attempted suiside with sleeping pills. The German officers then discussed if they should surrender or proceed to Japan. They decide to surrender and to kill the Japanese who had botched their suiside attempt. This meant that they could not talk to the Americans about the purpose of the uranium oxide. Their bodies were discaded at sea. The captain then contacted naval authjorities in Halifax to arrange a surrender. Finally he decided to surrender to the Americans. The USS Sumter escorted the U-234 to Portsmouth. The U-234 was interned at Portsmouth (May 19). There the Americans learned for the first time that radio-active uranium oxide was aboard. What the Americans did not know was if other U-boats had gotten through to Japan with uranium an nuclear technology. This may have influenced the subsequent American decession to use the bomb on Japan. The nature of the uranium and disposition by the U.S. Navy is shrouded in mystery. Using lead contianers with gold lining suggests it was very high grade enriched uranium, perhaps U235. [Hydrick, p.7.] As far as I know, the Government has never released the level of enrichment which would provide an insight into the German atomic program. It is generally accepted that the Los Alamos team was having trouble obtaining the amount of uranium needed for a bomb. [Goldberg] Some authors believe that the uranium on U-234 was used by the Americans to bomb Japan. Lt. Col. John Lansdale Jr. who worked with the Manhattan Project as a security officer an was responsible for tracking uranium. He says the German uranium was used to build the bombs dropped on Japoan. [Broad] Some authors also wonder about the "infrared proximity fuse" and wether it was actually a fuse connected with the atomic program. Many of these quetions are still unanswered. But the fact thsat the Germans had enrched uranium strongly suggests thsat they had made more progress in building a bomb than is recognized by most authors. And it raised the questions about the Japanese atomic bomb program and the extent of cooperation between the Axis allies.

Cooperation

Unlike the Anglo-American relationship, there sees to have been relatively limited scientific cooperation between Germany and Japan. What did occur was primarily German technology delivered to Japan. The Germans wanted to be paid. And they were concerned about the future relationship between the two countries. As the War went against Germany, the Germans were more willing to transfer technology. We know that the Japanese and Germans were cooperating on nuclear weapons because of Magic decrypts. These decrypts described efforts to share military technology and critical materials. We do not know the etent of this cooperation. We do do not know if the Germans briefed their Axis ally on what they were doing. We do know that the Japanese learned that the Germans had uranium. How they learned anout this we do not know. The fact that there was a Czech uranium mine was well known before the War. Ahnd we also know that the Japanese tried to hide the fact thst they had a nuclear weapons program even after requesring uramium, inventing the story that it was a catalyst to be used in the synthetic fuel industry. We do not know if the Japanese wre aware of thecfact that thecGermans had an uranium enrichment program.

Japanese Requests

We know that the Japanese attached great priority to obtaining uranium as part of their exchanges with the Germans. We are not sure if they specifically wanted enriched uranium or found out about the German enrichment program after requesting the uranium. We know about these requests because of the Magic decrypts. Primeminister Tojo ordered Colonel Kawashima (he may have been a general) to innitiate a Japanese atomic bomb project (fall 1942). His greatest problem was obtaining the adequate quantities of weapons grade uranium. needed for a Japanese atomic bomb. We know from NARA Magic decrypts that Kawashima attempted to obrain Uranium Pitchblende from the Germans. [Magic decrypt--Signal sent to the Japanese Embassy in Berlin, July 7, 1943.] The Germans wanted to know the purpose. Kawashima attempted to hide the purpose. He said it was for a catalyst to produce jet fuel from coal. The Germans either did not believe him or wanted details on the catalyst for their synthetic fuel program. [August 1943] This forced Kawashima's hand. He signaled the Japanese Embassy in Berlin explaining it was for a nuclear weapons project. [November 1943]

German Response

The Germans agreed to the shipments requested by the Japanese. The questuion for hostorians is why these exchanges came so late the the War. The Axis agreement was sugned even before Japan entered the War. And the Japanese-German relationship began even earlier. So one has to ask first why the Japanese did not immediately press for German technology and why the Germans were not more intent on providing their technology to the Japanese. This is all in sharp to the British providing the Americans its most advnced technology even before America entered the War. We suspect tghat the Japanese did not yet know how importaht high-tech weapons were and were not aware of just what the Germabs had to offer. The Japanese as esult of their Bushido code seemed to believe thst fighhting spirit was the central war-winning facor. The Germans for their part, were not all that anxious to share their high technology with allies, especially an ally they migh someday become a rival. And they wanted to get paid for technology transfer. This all changed as the War began the Germans and Japanese. The Germans had Uranium ore from Jac-y-mov (Joachimsthal) in western Czechoslovakia. It was partially refined at the Degaussa plant in Oranienberg. The Japanese were quite persistent. And because of the veery limited cargo space available, anything on the list was a stong indicator of the Japanese priorities. As far as we know, there were no nuclear requests from the Germans.

Uranium Oxide

One of the major questions about the German nuclear transfers to Japan concerns the quantity of the uranium transferred to Japan and the level of enrichment. We believe that what was shipped was uranium oxide which is what was found on the U-234. Uranium oxide was what the Japanese needed for the gaseous difusion method of enrichment. It is not known how much uranium the Germans shipped to Japan. Perhaps German naval records contain this data, but we have never seen any definitive assessment of these shipments. Some of these shipments were loss at sea and the Japanese are very reluctant to report on what they received. Another important question is the level of refinment of the uraniym oxide. Here we have seen a wide range of assessments from unrefined to near weapons grade (about 75 percent U-235). Unlike the amounts shipped, this is knowable because the U-234 surrendered to the Americans and the 560 kg of uranium oxide aboard was seized by the U.S. Navy and turned over to the Manhattan Project. Thus American sources know precisely what the level of the German refinement was. We have not yet, however, been able to find a definitive statemebt from the U.S. Government on thevlevel of refinement. Here we would be interested if readers know of any U.S. Government report released.

Transfers

Germany transferred considerable weapons technology to Japan. Once the War began because of the Royal Navy and later the U.S. Navy's control of the Atlantic this had to be done mostly by U-boat Just what cargos and scientific research papers got through to Japan is not known. Nor do we know if the Japanese just asked for the enriched U-235 on their own or if there were discussions about nuclear weapons. There could not have been technical discussions because as far as we know, Japanese phyicists never traveled to Germany or German pysicists to Japan. We only know that uranium must have been very high on the list of Japanese priorities to have been included on the last U-boat out of Germany to Japan. We do not know if the Germans transferred nuclear technology to Japan. The problem was how to transfer it. The Germans converted mine laying submarines to carry cargos. Allied command of the sea severely limited contacts between Axis allies Germany and Japan. Several German and Japanese submarines were involved in this effort because by the time the Japanese requested the uranium, surface transport was no longer possible. Many of the submarines involved in this effort were lost and very few survived to make round trips. How many carried nuclear materials or technology is unknow. Some information is available on individual submarines. Details on most of the submarine transports are hazy. We know a great deal about the last one--the U-234. This is because the captain surrendered to the Americans who recovered 560 kg of enriched uranium aboard. Researchers addressing this question are also interested in several individual submarines (U234, 871, 874, 876 as well as three Italian submarines. [Bybee]

Japanese I-class Submarines

The Japanese attempted to use their submarines to bring German enriched uranium back to Japan. The initial plan was to ship the uranium oxide (yellow cake) on Japanese I-class submarines. Several Japanese I-class submarines were dispatched to pick up uranium oxide from the Germans. Magic decrypts alerted the Allies. We do not yet have detailed information on the individual submarines involved. We believe that some made it to French Atlantic ports. The Japanese used Atlantic ports because of the dangers in passing through the Straits of Gibraltar by late-1943. As far as we can tell, none of the Japanese submarines made it back to Japan with uranium, although reports are hazy. This is impossible to verify, in part because Japanese sources are very reluctant to release information on their World War II atomic program. After D-Day and the Allied liberation of the French Atlantic ports, the Japanese made no further efforts to pick up the German uranium with their own submarines.

I-52 (June 1944)

The I-52 was the last Japanese submarines dispatched to pick up German uranium, As a result tthe I-52 is sometimes called "Japan's Golden Submarine". The Japanese gabe the missiion the ode name "Momi" (Fir Tree). The shiop was ordered to Lorient, in NAZI-occupied France. The I-52 was a C3 class boat on her maiden voyage. The cargo included rubber desperately needed by the Germans and other raw material along with 2 two tons of gold to pay the Germans for the uranium and to support Japanese diplomatic efforts in Europe. Also aboard were civilian engineers and technicians being loan to Germany and a crew of about 100 men. Through Magic decrypts, the Americans were awarecof the I-52 and tracking it. The I-52 rendezvoued with the German U-530 at night which provided a "Naxos" radar installation, two technicians to install it, and a pilot to get allow her to get through mine fields and safely into Lorient (June 23). The Allies were tracking both submarines. The signals used to rendezvous with the Germans hepped the U.S. Navy find the I-52. Soon after the at sea transfer, aircraft from the USS Bogue found and attacked the I-52. [Billings] The Anerucan flyers depth charged the I-52 and then torpedoed it on the surface. The I-52 sanl with the loss of 109 Japanese and 3 German lives. American underwater explorer Paul Tidwell located and filmed the wreck (1995).

Italian Submarines

The Italian Navy had transport submarines. Apparently the Germans used some ofthese ships for Japan transport operations even after the Itaian surrender to the Allies (September 1943). They may have been employed in the efforts to get uranium to Japan. We have noted the UIT-24 and UIT-25 mentioned. We have not been able to find any reliable data if these ships actually departed with uranium aboard and if any made it through to Japan.

German Submarines

Much more information exists on the German U-boats involved in these transfers, in part because of the availability of German naval records. The Germances do not seem especially anxious to transfer advanced weapons technology to Japan early in the War, even after the signing of the Ac=xis Treaty. This changed decidedly after the war turned against Germany. Apparently Hitler and German commabders hoped that prociding Japan with advanced weapons might divert American priorities to the Pacific. After the Allies shut down surface ships moving between Japan and Germany, the Axis allies began using submarines. The Allies accomplisged this before the Japanese requested uranium. Tgus all tge nuclear trahnsfers were conducted by submarine. This occurred through French Atlantic ports until D-Day. After D-Day closed the French ports, the Germans agreed to send the Japanese uranium oxide on out-bound U-boat shipments from Germann ports (August 1944). This was by late-1944 very dangerous because of increasingky effective Allies anti-submarine warefare (ASW) actions.

U-180 (February 1943)

Axis transpots became very dangerous as the Allies improved their ASW technology. The U-180 was one of the few German U-boats to make a round trip in these Axis transports. The U-180 was a Type IXD1 transport U-boat. She was sripped of torpedo armament to create more cargo capacity. The Type IXD1s were designated as transport submarines, and could carry up some 250 tons of freight. The U-180 in its short life was used primarily for clandestine operations. The U-180 under the commnd of Fregattenkapitän Werner Musenberg sailed from Kiel (February 9, 1943) carrying the leader of the Indian National Army Subhas Chandra Bose and his aide Abid Hasan. The British victory at El Alemaine meant that the Germans coild notg reach India. The Japanese wre, however, on he eastern border of Inia. U-180 rendezvoued with the Japanese submarine I-29, just east of Madagascar (April 21). The Indians were exchbged for two Japanese Navy officers, shipbuilding specialisrs. Captains Emi Tetsushiro and Tomonaga Hideo, had orders to study U-boat building techniques. Bose and Hasan's transfer is the only known record of a civilian transfer between two submarines of two different navies during World War II. The Japanese also trabsferred two tons of gold ingots in payment for German weapons technology and support embassy operations. U-boats were not designed fir such extebded missions. U-180 was supplied by U-462 on the way to the Indian Ocean exchange. She was supposed to be refueled by U-463 on the return voyage. The Allies by this time had vastly inporved theur ASW capbility abd sank U-462 (May 16). So U-530 refuled U-180. Oberleutnant zur See Rolf Riesen took commad of U190 for its econd patrol from Bordeaux (August 20 1944) just befire the allies seized the port. She did not ger far. By this time it was a virtual suiside missin for U-boats. The Allies sabk U-180 in the Bay of Biscay (August 23).

U-859 (April 1944)

The U-859 was a Type IXD2 U-boat built during World War II. It was assigned to the Monsun Gruppe (Monsoon Group) which operated in the Far East out of Penang in Japanese occupied Malaya. The Monsun Gruppe theoreticlly was to noperate ro support the the Imperial Japanese Navy, which actually had a very large submarine fleet of its own. As it worked out, the Japanese were very suspicous off the German U-boats and provided little support. After construction a Snorkel to enable her to stay underwater for longer during the hazardous passage to the Indian Ocean. This delayed deployment. She departes Kiel (Spring 1944). Some authors believe the boat carrird uranium oxide. The boat was intercepted in the Malacca Straits just a few km from Penang. HMS Trenchant sank the U-859 (Septemnber 23, 1944). Divers after the War found 12 tons mercury aboard, but no uranium (1972).

U-864 (February 1945)

The U-864 a Type IX U-boat which was was used as a Japan transport. Type IX was a large U-boat used for long range operations, but was not as maneurable as the smaller Type VII which was the primary type used for combat operations by the Kriegsmarine. Magic/Ultra intercepts revealed that she had a mission of transporting military equipment to Japan. The Norwegian Underground also provided information. German U-boats at the time were still using Norwegian bases. In fact with theliberation of France. the Norwegian bases became even mote important. The Germans report that she carried 67 tons of metallic mercury in 1,857 32 kg steel flasks stored in her keel. The Japanese had purchased the mercury from Axis ally Italy before that country surrendered to the Allies. The mercury was needed for missle and tirpedo detonation systems. The U-864 also carried parts and engineering drawings for the German jet fighter and other military supplies. The Japanese hoped that could restablish some air potential with the advanced German technology. Hope was lrgely gone for the Reich. A stiffer Japanese war effort might relieve pressure in Europe. [Preisler and Sewell] The intgeresting question of course is why did the Axis take so long to cooperate. There were also German and Japanese scientists. Among her passengers were Messerschmitt engineers Rolf von Chlingensperg and Riclef Schomerus, Japanese torpedo expert Tadao Yamoto, and Japanese fuel expert Toshio Nakai. Japanese Col. Kawashima claims a U-boat with 2 tons of uranium oxide was sunk. [Kawashima] Kawashima did not specify the U-boat or where it was sunk, but he was probably referring to the U-864. [Chen] Alerted to the U-864's mission bu Ultra, the British launched bombing raids hoping to catch the U-boat in port. Then the hunt began for the U-864. Preisler and Kenneth Sewell] The U-864 departed Kiel (December 5, 1944). The voyage was, however, delayed by first an accident and then a British air raid on the Bergen U-boat pens where the ship was being repaired raid (January 12, 1945). While undergoing trials it was engaged by the British submarine HMS Venture and sunk in Norwegian coastal waters (February 9). [Preisler and Sewell] This was the only intentional submerged sinking of a submarine by another submarine during the War. Venture had an advantage because the U-864 ws so large and less manueverable. The remains of the U-864 are known, but there is no confirmation that uranium was aboard. The wreck was found (2003), but has not yet been carefully investigated. by the Norwegian Coastal Authority (NCA). We know that it was carrying mercury because a cannister with mercury has been retrieved from the wreck. While uranium is suspected, it has not yet been proved.

U-873 (March 1945)

The U-873 was a type IX D-C, modified from a IX D-2. The boat had a helicopter for reconisance purposes, but was removed for the final patrol. She was assigned to deliver material to Japan. For this purpose a Snorkel was added (for undferwater running) and a half deck was added. Departure was delayed when the boat was damaged by an air attack (July 30, 1944). After repairs and trials, the boat was loaded with its cargo at Kiel (January 6, 1945). We are not sure what that cargo was. New orders were received and 14 pasangers. The crew told U.S. Navy interogators that the orders came personally from Hitler that all -boats be made ready for war patrols. U-873 departed Kiel for Horten, Norway and additional trials (February 17), but was damaged. The boat did not finally leave on its first war patrol until, without any passengers (March 3). This was a Caribbean patrol, not a Japan transport. As it had to run submerged, it received few signals. It did learn of the NAZI surrender and orders to return to Norway (May 7). The officers and crew debated what to do. The officers wanted to head for Argentina and sell the cargo. The crew insisted that they follow instructioins broadcasted by the Allies. They finally set sail for America and radioded Allied authorities (May 11). Some equioment and papers were jettidoned, certainly the code equipment and related material. She arrived in Portsmouth, New Hampshire (May 17). [U.S. Navy. Op 16 Z.]

U-234 (April 1945)

The mission of the U-234 continues to be one of the unresolved mysteries of Worlsd War II. The U-234 was a very large mine-laying U-boat--the XB type mine layer. Because of its size it was converted as a Japan transporter, thus becoming an undersea freighter to carry a much larger cargo than a standard U-boat. Even so it held only a fraction of the cargo of a surface merchant vessel. The U-234 was dispacted to Japan with a cargo of German high-tech equipment. The U-234 departed Kiel headed for Kristiansand, Norway (March 25, 1945). The ship departed Norway for Japan (April 16, 1945). The cargo included drawings, a Me-262 jet fighter in crates, air defense radars and jet engine equipment as well as two German experts on various weapons technologies and two Japanese officers. What made the U-234 especially interesting was 80 gold-lined lead cylinders containing 560 kilograms of uranium oxide marked "For the Japanese Army". There is very limited cargo space even aboard this cargo U-boat. Thus only items of the highest priority would have been loaded. Cpt. Fehler received cease-fire orders (May 4). He decided to surrender to the Americans. The Captain claimed to know nothing about the uranium. The only pupose for the uranium oxide given the state of Japanese nuclear research would have been a dirty bomb. Also aboard were two Japanese officer--Air Force Colonel Genzo Shosi, an aeronautical engineer, and Navy Captain Hideo Tomonaga, a submarine architect. The U-234 was informed of Hitler's suicide (May 1). Naval Highcommand ordered all German submarines to observe a ceasefire (May 4). The order to surrender was then given (May 8). The captain of the U-234 at this time arrested the Japanese officers who subsequently attempted suiside with sleeping pills. The German officers then discussed if they should surrender or proceed to Japan. They decide to surrender and to kill the Japanese who had botched their suiside attempt. This meant that they could not talk to the Americans about the purpose of the uranium oxide. Their bodies were discaded at sea. The captain then contacted naval authjorities in Halifax to arrange a surrender. Finally he decided to surrender to the Americans. The USS Sumter escorted the U-234 to Portsmouth. The U-234 was interned at Portsmouth (May 19). There the Americans learned for the first time that radio-active uranium oxide was aboard. What the Americans did not know was if other U-boats had gotten through to Japan with uranium an nuclear technology. This may have influenced the subsequent American decession to use the bomb on Japan. The nature of the uranium and disposition by the U.S. Navy is shrouded in mystery. Using lead contianers with gold lining was needed because uranium is highly corrisive. This and the lead cannisters susts it was a very high grade enriched uranium. [Hydrick, p.7.] The level of enrichment refers to the percentagecof the U-235 isotope. As far as we know, the Government has never released the level of enrichment which would provide an insight into the German atomic program. It is generally accepted that the Los Alamos team was having trouble obtaining the amount of uranium needed for a bomb. [Goldberg] Some authors believe that the uranium on U-234 was a godsend for the American Manhattan Project and used by the Americans for the bombs used on Japan. Lt. Col. John Lansdale Jr. who worked with the Manhattan Project as a security officer and was responsible for tracking uranium confirms that the German uranium was used to build the bombs dropped on Japan. [Broad] Some authors also wonder about the "infrared proximity fuse" and wether it was actually a fuse connected with the atomic program. Many of these quetions are still unanswered. But the fact that the Germans had enriched uranium strongly suggests that they had made more progress in building a bomb than is recognized by most authors. And it also raises questions about the Japanese atomic bomb program and the extent of cooperation between the Axis allies.

U-530 (March-May 1945)

After the War, Argentina with a Government sympsthetic to European Fascists and a substantial Germnan minority was seen as potential safe haven by NZI war criminals attempting to escape Allied justice. Rumors of such an effort were fueled by two German U-boats which showed up off Argentina after the War. The first such U-boat was U-530. Oberleutnant Otto Wermuth did not surrender as ordered at the end of the War. Rather the boat headed for Argentina, a dangerous voyage at the time. Wemuth surrendered at Mar del Plata to the Argentine Navy (July 10, 1945). Wermuth jettisoned its deck gun, the crew carried no identification, and the ship's log disappeared. Wermuth did not explain his actions. U-530 was configured for transport rather than normal combat. There are rumors that it was part of a planned nerve gas attack on New York City, but there is no solid evidence. Transport of uranium or secret technology is another possibiliy.

Sources

Billings, Richard N. Battleground Atlantic: How the Sinking of a Single Japanese Submarine Assured the Outcome of World War II, 311p.

Broad, William J. "A-bomb program used Nazi uranium: Material was aboard submarine that surrendered in 1945," Ocala Star Banner (Secember 30, 1995). Broad wrote for the New York Times which was syndicated to other newspapers.

Bybee, John D. E-mail nessage, August 3, 2011.

Chen, P.Y. "Allied sinking of German u-boat hindered Japanese abomb project,".

Goldberg, Stanley.

Hydrick, Carter P. Critical Mass: The Real Story of the Atomic Bomb and the Birth of the Nuclear Age.

NARA Magic decrypts.

Preisler, Jerome and Kenneth Sewell. Code Name Caesar: The Secret Hunt for U-Boat 864 during World war II (2012), 302p.

U.S. Navy. Op 16 Z. Report on interogation of the crew of the U-873 which surrendered to the USS Vaance on 11 MAY 1945, in position 35°-45'N - 42°-31'W" (Junw 26, 1845).





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Created: 1:00 AM 4/6/2011
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