Bundesmarine — :. From September until his capture in March he sank 44 ships, including one warship, a total of , tons. He earned the nickname "Silent Otto", both for his successful use of the " silent running " capability of U-boats and for his reluctance to transmit radio messages during patrols.
After the war he served in the German Federal Navy, from which he retired in with the flag rank of commodore. He then moved to a Realgymnasium secondary school. Kretschmer indulged in sporting pastimes and scientific interests.
Kretschmer achieved good results in mathematics and chemistry and passed his Abitur school-leaving certificate at The report contained the remark, "Kretschmer demonstrated his extraordinary courage in many instances.
He wants to be a naval officer. He mastered the English language and came to respect British education: its practical focus complemented his scientific and theoretical—based German background. His time in England shaped his view of them during the war; he was quick to believe in rumours of new British inventions during the war at sea.
He did not return to England from his hiatus, but travelled through France, Switzerland and Italy. Kretschmer formed part of "Crew 30" the incoming class of , 78—strong intake of officer candidates. On 2 October , Kretschmer was transferred to the pocket battleship Deutschland as a gunnery officer during a trip to Denmark.
