German submarine U - 234 German submarine " U - 234 " was a Type XB U - boat of the Nazi German " Kriegsmarine " during World War II . Her first and only mission into enemy territory consisted of the attempted delivery of uranium oxide and German advanced weapons technology to the Empire of Japan . After learning of Germany ' s unconditional surrender , the submarine ' s crew surrendered to the United States on 14 May 1945 . Construction . Originally built as a minelaying submarine , she was laid down at the " Germaniawerft " yard in Kiel on 1 April 1942 ; " U - 234 " was damaged during construction , but launched on 22 December 1943 . Following the loss of in July 1944 , it was decided not to use " U - 234 " as a minelayer ; she was completed instead as a long - range cargo submarine with missions to Japan in mind . Sensors . Radar . " U - 234 " was one of the few U - boats that was fitted with a FuMO - 61 " Hohentwiel " U - Radar Transmitter . This equipment was installed on the starboard side of the conning tower . Radar Detection . " U - 234 " was also fitted with the FuMB - 26 " Tunis " antenna . Wartime service . " U - 234 " returned to the " Germaniawerft " yard at Kiel on 5 September 1944 , to be refitted as a transport . Apart from minor work , she had a snorkel added and 12 of her 30 mineshafts were fitted with special cargo containers the same diameter as the shafts and held in place by the mine release mechanisms . In addition , her keel was loaded with cargo , thought to be optical - grade glass and mercury , and her four upper - deck torpedo storage compartments ( two on each side ) were also occupied by cargo containers . Cargo . The cargo to be carried was determined by a special commission , the " Marine Sonderdienst Ausland " , established towards the end of 1944 , at which time the submarine ' s officers were informed that they were to make a special voyage to Japan . When loading was completed , the submarine ' s officers estimated that they were carrying 240 tons of cargo plus sufficient diesel fuel and provisions for a six - to nine - month voyage . The cargo included technical drawings , examples of the newest electric torpedoes , one crated Me 262 jet aircraft , a Henschel Hs 293 glide bomb and what was listed on the US Unloading Manifest as 560 kg of uranium oxide . As evidenced by Hirschfeld and Brooks in the 1997 book " Hirschfeld " , Wolfgang Hirschfeld reportedly watched the loading into the boat ' s cylindrical mine shafts of about 50 lead cubes with nine inch ( 230 mm ) sides , with " U - 235 " painted on each . According to cable messages sent from the dockyard , these containers held " U - powder " . Author and historian Joseph M . Scalia , stated that he discovered a formerly secret cable at Portsmouth Navy Yard , the uranium oxide had been stored in gold - lined cylinders ; this document is discussed in " Hitler ' s Terror Weapons " . The exact characteristics of the uranium remain unknown ; it has been suggested by Scalia , and historians Carl Boyd and Akihiko Yoshida that it may not have been weapons - grade material and was instead intended for use as a catalyst in the production of synthetic methanol for aviation fuel . When the cargo had been loaded , " U - 234 " carried out additional trials near Kiel , then returned to the northern German city where her passengers came aboard . Passengers . " U - 234 " was carrying twelve passengers , including a German general , four German naval officers , civilian engineers and scientists and two Japanese naval officers . The German personnel included General Ulrich Kessler of the " Luftwaffe " , who was to take over " Luftwaffe " liaison duties in Tokyo ; Kai Nieschling , a Naval Fleet Judge Advocate who was to rid the German diplomatic corps in Japan of the remnants of the Richard Sorge spy ring ; Dr . Heinz Schlicke , a specialist in radar , infra - red , and countermeasures and director of the Naval Test Fields in Kiel ( later recruited by the USA in Operation Paperclip ) ; and August Bringewalde , who was in charge of Me 262 production at Messerschmitt . The Japanese passengers were Lieutenant Commander Hideo Tomonaga of the Imperial Japanese Navy , a naval architect and submarine designer who had come to Germany in 1943 on the Japanese submarine " I - 29 " , and Lieutenant Commander Shoji Genzo , an aircraft specialist and former naval attaché . Final voyage . " U - 234 " sailed from Kiel for Kristiansand in Norway on the evening of 25 March 1945 , accompanied by escort vessels and three Type XXIII coastal U - boats , arriving in Horten two days later . The submersible spent the next eight days carrying out trials on her snorkel , during which she accidentally collided with a Type VIIC U - boat performing similar trials . Damage to both submarines was minor , and despite a diving and fuel oil tank being holed , " U - 234 " was able to complete her trials . She then proceeded to Kristiansand , arriving on about 5 April , where she underwent repairs and topped up her provisions and fuel . " U - 234 " departed Kristiansand for Japan on 15 April 1945 , running submerged at snorkel depth for the first 16 days , and surfacing after that only because her commander " Kapitänleutnant " Johann - Heinrich Fehler , considered he was safe from attack on the surface in the prevailing severe storm . From then on , she spent two hours running on the surface by night , and the remainder of the time submerged . The voyage proceeded without incident ; the first sign that world affairs were overtaking the voyage was when the German Navy ' s Goliath transmitter stopped transmitting , followed shortly after by the Nauen station . Fehler did not know it , but Germany ' s naval HQ had fallen into Allied hands . Then , on 4 May , " U - 234 " received a fragment of a broadcast from British and American radio stations announcing that Admiral Karl Dönitz had become Germany ' s head of state following the death of Adolf Hitler . " U - 234 " surfaced on 10 May in the interests of better radio reception and received Dönitz ' s last order to the submarine force , ordering all U - boats to surface , hoist black flags and surrender to Allied forces . Fehler suspected a trick and managed to contact another U - boat ( ) , whose captain convinced him that the message was authentic . At this point , Fehler was practically equidistant from British , Canadian and American ports . He decided not to continue his journey , and instead headed for the east coast of the United States . Fehler thought it likely that if they surrendered to Canadian or British forces , they would be imprisoned and it could be years before they were returned to Germany ; he believed that the US , on the other hand , would probably just send them home . Fehler consequently decided that he would surrender to US forces , but radioed on 12 May that he intended to sail to Halifax , Nova Scotia to surrender to ensure Canadian units would not reach him first . " U - 234 " then set course for Newport News , Virginia ; Fehler taking care to dispose of his " Tunis " radar detector , the new " Kurier " radio communication system , and all Enigma related documents and other classified papers . On learning that the U - boat was to surrender , the two Japanese passengers committed suicide by taking an overdose of Luminal ( a barbiturate sleeping pill ) . They were buried at sea . Capture . The difference between Fehler ' s reported course to Halifax and his true course was soon realized by US authorities who dispatched two destroyers to intercept " U - 234 " . On 14 May 1945 she was encountered south of the Grand Banks , Newfoundland by the . Members of the " Sutton ' s " crew took command of the U - boat and sailed her to the Portsmouth Naval Shipyard , where " U - 805 " , " U - 873 " , and " U - 1228 " had already surrendered . News of " U - 234 ' s " surrender with her high - ranking German passengers made it a major news event . Reporters swarmed over the Navy Yard and went to sea in a small boat for a look at the submarine . The fact that she had a half ton of uranium oxide on board was covered up and remained classified for the duration of the Cold War ; a classified US intelligence summary of 19 May merely listed " U - 234 " ' s cargo as including drawings , arms , medical supplies , instruments , lead , mercury , caffeine , steels , optical glass and brass . The uranium subsequently disappeared , most likely finding its way to the Manhattan Project ' s Oak Ridge diffusion plant . It has been calculated that it would have yielded approximately of U - 235 after processing , around 20 % of what would have been required to arm a contemporary fission weapon . Dr . Velma Hunt , a retired Penn State University environmental health professor , has suggested " U - 234 " may have put into two ports between her surrender and her arrival at the Portsmouth Navy Yard : once in Newfoundland , to land an American sailor who had been accidentally shot in the buttocks , and again at Casco Bay , Maine . The US Navy reportedly unloaded about of uranium oxide from " U - 234 " at Portsmouth . Fate . As she was unneeded by the US Navy , " U - 234 " was sunk off Cape Cod as a torpedo target by the on 20 November 1947 .