German submarine U-859 was a Type IXD2 U-boat built for Nazi Germany's Kriegsmarine during World War II. She was one of a select number of U-boats to join Monsun Gruppe or Monsoon Group, which operated in the Far East alongside the Imperial Japanese Navy. Construction U-859 was built in Bremen during 1942 and 1943, and was heavily adapted following her completion in July 1943, with the addition of a snorkel to enable her to stay underwater for longer during the hazardous passage to Penang in Malaya. Thus she was not ready for war service until the spring of 1944, when following her working up period and modifications she departed Kiel for the East. Design German Type IXD2 submarines were considerably larger than the original Type IXs. U-859 had a displacement of when at the surface and while submerged. The U-boat had a total length of , a pressure hull length of , a beam of , a height of , and a draught of . The submarine was powered by two MAN M 9 V 40/46 supercharged four-stroke, nine-cylinder diesel engines plus two MWM RS34.5S six-cylinder four-stroke diesel engines for cruising, producing a total of for use while surfaced, two Siemens-Schuckert 2 GU 345/34 double-acting electric motors producing a total of for use while submerged. She had two shafts and two propellers. The boat was capable of operating at depths of up to . The submarine had a maximum surface speed of and a maximum submerged speed of . When submerged, the boat could operate for at ; when surfaced, she could travel at . U-859 was fitted with six torpedo tubes (four fitted at the bow and two at the stern), 24 torpedoes, one SK C/32 naval gun, 150 rounds, and a Flak M42 with 2575 rounds as well as two C/30 anti-aircraft guns with 8100 rounds. The boat had a complement of fifty-five. Service history Although U-859 only had a single war patrol from which she never returned, her six month career was highly eventful and carried her halfway across the world and into an entirely different theatre of conflict. Commanded by Kapitänleutnant Johann Jebsen, U-859 sailed from Kiel for Penang on 4 April 1944, carrying 31 tons of mercury in metal flasks destined for use in the Japanese munitions industry. She avoided shipping lanes and during her time in the North Atlantic, remained submerged for 23 hours