During the first eight months of World War II, Kretschmer conducted eight patrols in U–23 in the North Sea near the coast of Great Britain but achieved little success due to the limited capabilities of his submarine. His most notable achievements were sinking a tanker in January 1940 and the destroyer HMS Daring in February 1940. In April 1940, Kretschmer took command of U–99, a much larger and more capable Type VII submarine. After two months of intensive training with his crew, he began the first of eight patrols into the Atlantic in June 1940.
During these patrols, Kretschmer refined his tactics of slipping into the middle of convoys at night and torpedoing ships from the surface, often at very close range. The success of these attacks spawned his motto "One torpedo, one ship." He also earned recognition for sinking three British armed merchant cruisers in November 1940, including two on the night of 3–4 November in a running surface engagement in which he utilized his 88 mm deck gun. This action helped to convince the British Admiralty to discontinue the use of such ships. Kretschmer was the first German submarine commander to sink 250,000 tons of Allied shipping.
The most successful U-boat commander of the war, Kretschmer was known as "the tonnage king" because of his exploits. From September 1939 to March 1941, he sank 47 merchant ships totaling 273,503 tons and earned Germany's highest award for bravery, the Knight's Cross with Oak Leaves and Swords to the Iron Cross. Kretschmer, however, eschewed efforts to propagandize his accomplishments, earning another nickname, "Silent Otto." On 17 March 1941, he successfully attacked the 10-ship HX.112 convoy south of Iceland. After expending his torpedoes, he was returning to base in France when two British destroyers attacked and sank his boat. He and 40 of his 43-man crew were rescued.
Kretschmer spent the remainder of the war as a prisoner of war in Canada, returning to Germany in December 1947. In 1955, he joined the postwar navy of the Federal Republic of Germany, the Bundesmarine, and in 1965, he became chief of staff of the North Atlantic Treaty Organization (NATO) Baltic Command, a position he held for four years. He retired in 1970 with the rank of Flotillenadmiral (U.S. equiv. rear admiral). Kretschmer died at Straubing, Germany, on 5 August 1998.
C. J. Horn
Bekker, Cajus. Hitler's Naval War. New York: Zebra Books, 1974.; Blair, Clay. Hitler's U-Boat War. Vol. 1, The Hunters, 1939–1942. New York: Random House, 1996.; Doenitz, Karl. Memoirs: Ten Years and Twenty Days. Trans. R. H. Stevens in collaboration with David Woodward. Annapolis, MD: Naval Institute Press, 1990.