Hellmuth von Ruckteschell (22 March 1890 − 24 September 1948) was a German naval officer during World War II; he was one of the most successful merchant raider commanders of Nazi Germany, serving as the captain of the commerce raiders Widder and Michel. After the war Ruckteschell was convicted of war crimes and died in prison. Naval career Born in 1890 in Hamburg, Ruckteschell joined the German navy in 1908. In 1916, with the rank of Oberleutnant zur See, he transferred to the U-boat arm. He served as Watch Officer on and , before being given his own command in July 1917, first of , then in March 1918, of . He earned a reputation as an overly aggressive commander, which caused him to be placed on a black-list of officers the Allied powers considered to have breached the laws of war. After the end of World War I, he left Germany returning in the early 1930s. Ruckteschell was recalled to duty in the Kriegsmarine in 1939 and given command of an auxiliary minelayer. He next took command of the and sailed her into the Atlantic Ocean on 6 May 1940, commencing a five-month cruise that would sink or capture ten enemy merchant ships. When he brought Widder into port at Brest, he refused the Naval Command's order to take the ship to Hamburg, because the passage through British controlled territory was too risky. Instead, he assumed command of the commerce raider for her first cruise (9 March 1942 to 1 March 1943), during which he captured or sank fifteen ships. Von Ruckteschell was relieved when he arrived in Japan at his own request for health reasons. Ruckteschell was one of the more successful raider captains. The success of a commerce raider is measure by both the tonnage destroyed and the time spent at large. Ruckteschell accounted for (second only to Ernst-Felix Krüder of Pinguin) and stayed at large for 538 days, (second only to Bernhard Rogge of Atlantis); however, Ruckteschell accomplished this over two voyages. Of the 13 voyages by 10 raiders, Michel and Widder claimed 15 ships of , and 10 ships of (4th and 6th highest), and stayed at large for 358, and 180 days ( 4th and 9th longest). War crimes trial Ruckteschell was the subject of one of the first war crimes investigations undertaken by the British Admiralty. It was alleged that on several occasions