Figure 1.--.

The mission of the U-234 continues to be one of the unresolved mysteries of World 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 percentage of 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.

The Boat

The U-234 was a very large mine-laying U-boat--the IX-B 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 is a good example of how the Allied strategic bombing campaign impaired the German war effort. The U-234 had its keel laid down (September 1942), but it never made a combat patrol. It was struck by a bomb while on the building ways (May 1943). A forward section about 9 meters in length was severely damaged and had to be completely replaced. It was finally launched (December 1943) and commissioned (March 1944). [U.S. Navy] By that time the Admoral Dönitz's U-boats had lost the ll-importnt Battle of the Atlantic and Allied ASW operation had actually made it dangerous for U-boats to venture out into the Atlantic. The U-23 Its only mission was the cargo assignmnt to Japan.

The Mission

The U-234 was dispacted to Japan with a cargo of German high-tech equipment. We do not know precisely who gave the orders for the mission. We would guess that Hitler may have been conulted, but we have no direct evudence of this.

Cargo Decisions: Marine Sonder Dienst Auslands

Unlike the massive American Lend Lease aid to Britain and the Soviet Union, the use of U-boats severely restricted what could be transported to Japan. Thus what was to ba carried in these U-boat runs had to be carefully thought out. The U.S. Navy reports, "The actual loading of U-234 and the type of cargo she was to carry was determined by a special commission formed in December, 1944. At this time, it was made known to the officers of U-234 that they were to go to Japan. The special commission known as the “Marine Sonder Dienst Auslands”, headed by K.K. Becker, was in charge of all details and determined what cargo was to be carried. Klt. Longbein from this commission was the actual loading officer. Loading containers were designed of the same diameter as the vertical mine shafts and were loaded in the shafts and held in place by the original mine releasing mechanism. The four compartments, two on either side, were loaded with horizontal tubes, (these tubes were originally above deck torpedo containers and were merely shortened somewhat and used as cargo containers). U-234 then carried six cargo containers in the mine shafts forward and amidships; six vertical containers in the mine shafts on either side, and in each of the four cargo spaces were eight horizontally placed cargo tubes. Four cargo containers, two on either side, were carried topside. The ship’s officers estimated that 240 tons of cargo were aboard in addition to fuel and provisions for a six to nine month’s trip." [U.S. Navy]

Cargo

The cargo included drawings, a Me-262 jet fighter in crates, air defense radars and jet engine equipment. What made the U-234 especially interesting was 80 gold-lined lead cylinders containing 560 kilograms of uranium oxide marked "For the Japanese Army". Using lead contianers with gold lining was needed because uranium is highly corrisive. 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. There is very limited cargo space even aboard this cargo U-boat. Thus only items of the highest priority would have been loaded.

Voyage

The U-234 departed Kiel headed for Kristiansand, Norway (March 25, 1945). The ship departed Norway for Japan (April 16, 1945). 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 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. The captain then contacted Allied 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).

Passageners

The U-234 had Japanese and German weapons specialists aboard. Also aboard were two Japanese officer--Air Force Colonel Genzo Shosi, an aeronautical engineer, and Navy Captain Hideo Tomonaga, a submarine architect. The Germans decided 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, although it is not clear how much they knew. Given their backgrounds they probably did not know a great deal. Their bodies were discaded at sea. There were also two German weapons experts. Ulrich Kessler was a Luftwaffe general was a Prussian-born diplomat and military strategist who began his military career as a naval officer. He resigned his commission (1933). He joined the new Luftwaffe and commanded Stuka squadrons operating in Poland, Norway, and France (1939-40). He subsequently commabded special bombing attaxk squadorns in Norway. Kessler apparently did not get along with Luftwaffe commabnder Goering. There are rumors he was active in anti-Hitler resistance activities, including the July bomb plot. Kessler was on the U-234 to advise the Japanese in combat tactics using squadrons of ME-262 and ME-163 aircraft against Allied bombers. Submarine officers would not have know about Germany's secret nuclear program and there is no reaon to think they knew how the uranium was to be used. Kessler is a different matter. He may well have know, perhaps even briefed, but there is no way of knowing this. When the U-234 surrenderd in Portsmouth, Kessler surrendered with a smart salute. One source contends that it was Kessler who convinced Cpt. Fehler to surrender. One source suggests this was the case. [Grover] As senior officer, he would have had some influence and may have explained the significance of the uranium. Kessler claimed during interrogation that he had voluntered for the assignment as way of getting to Argentina. This could be true as many Germans wwre seeking refuge there. This is interesting because it is an open question to what extent the Argentines allowed U-boats to land or reprivision there.

U.S. Navy Interogation

This what the U.S. Navy learned after interogating the crew:

U-234 left Kristiansand on 15 April, 1945, with a conviction among all hands that Japan would never be reached. In fact, the commanding officer was stated to have told his crew that although they were officially destined for Japan, he was firmly convinced in his own mind that their destination would never be reached. U-234 proceeded submerged and at Schnorchel depth for the first 16 days and surfaced for the first time shortly before the Rosengarten, because of a severe storm. From then on she usually ran two hours on the surface at night and spent the balance of the time submerged to depths between 40 – 100 meters. She had orders not to make any attacks, so about the only incident before news of German’s surrender came was when she almost rammed a large steamer, but U-234 herself was not observed. The first ominous sign was when the Goliath station fell out and shortly after passing the Rosengarten no further signals were received from Nauen. From then on, all signals received were short wave. They had no radio contact for several days after the last message was received from Nauen. The U-boat series had been changed over to “Distel” series of which U-234 was ignorant. Then on the 4th of May, she got a fragmentary repeat from English and American stations about Dönitz’s elevation to supreme command in Germany. She was finally forced to surface in order to receive complete signals.

On 10 May, U-234 picked up the order for all U-boats to surrender and to proceed to an Allied port depending on their position at that time. Upon receipt of this message, considerable discussion arose among the officers and passengers as to what course they should follow. Eire was first mentioned and this proposal was enthusiastically received by the two Japanese officers aboard. The discussion was particularly heated because at the time the surrender signal was received U-234 was exactly on the dividing line which determined whether she should proceed to England or to an American port. During the following two or three days after the surrender order was received, she proceeded southerly, surfacing at night and submerging during the daytime. Messages from other U-boats obeying the surrender order were picked up by U-234 and led her to report her position. She first tried the international short wave band but her signals apparently were not received so she switched to the 600 meter wave band and it was several hours before an answer was received to this signal. U-234’s first direct orders were from England on short wave, received on the 12 of May at about 0800. Then late that evening, she received orders from Halifax to report her position and speed hourly.

When it became apparent to the Japanese officers that FEHLER intended to obey surrender orders, they informed the commanding officer of their resolve to commit suicide. FEHLER made some attempt to dissuade them from this, particularly by citing the surrender of Gen. Oshima and his staff as an example. But the pair requested that they be allowed to remain undisturbed in their cabin, which was granted. Previously, numerous gifts had been distributed among the officers and passengers. FEHLER received a Samurai sword, which he later threw overboard, and a sizeable sum in Swiss francs. A guard was placed outside their compartment, and the two took a dose of Luminol. They were still alive some 36 hours later, much to the disgust of the crew, and efforts on the part of the ship’s doctor to revive them failed. They were buried at sea on 11 May. Letters of thanks and appreciation addressed to FEHLER were found afterwards, also a request that an enclosed signal be sent to Japan. FEHLER did not comply with this request.

The first report made by U-234 as to her position and speed was accurately given but from then on she gave her speed as eight miles when she actually was doing between 12 and 15 and she was proceeding more westerly than indicated. Observation of her position by an airplane apparently resulted in the order from Halifax that she was to report hourly. The commanding officer of U-234 assumed that none of his hourly reports reached Halifax. At 2300Z on 14 May, U-234 was contacted by the USS SUTTON and a prize crew was placed aboard her. She arrived in Portsmouth on 17 May.

The Uranium

It was at Portsmouth that the Americans learned for the first time that radio-active uranium oxide was aboard. The nature of the uranium and disposition by the U.S. Navy is shrouded in mystery. The only pupose for the uranium oxide given the state of Japanese nuclear research would have been a dirty bomb. This and the lead cannisters suggest that the uranium oxide was a very high grade enriched uranium. [Hydrick, p.7.] The level of enrichment refers to the percentage of the U-235 isotope needed to achieve fission. As far as we know, the Government has never released the level of enrichment which would provide an insight into the German atomic program. We have seen various assessments from unprocessed to highly enriched. Unprocessed is not accurate because uranium oxide is a processed form. Just how enriched it was we are not yet sure. One source tells us that it was highly enruiched--65-70 percent. [Griover] This would be near bomb grade ahd even without a thermo-nuclear devise could be used for deadly dirty bombs. If the Germans had suceeded in enriching uranium, this 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. 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]

Americam Assessment

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.

Sources

Goldberg.

Grover, Wayne. E-mail message, April 7, 2011.

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

U.S. Navy. "REPORT ON INTERROGATION OF THE CREW OF U-234 WHICH SURRENDERED TO THE USS SUTTON ON 14 MAY, 1945, (Op-16-FA-4).

Created: 1:00 AM 4/6/2011
Last updated: 3:16 AM 7/15/2016