Karl-Friedrich Merten (15 August 1905 – 2 May 1993) commanded the U-boat in Nazi Germany's Kriegsmarine during World War II. He received the Knight's Cross of the Iron Cross with Oak Leaves. Merten was credited with the sinking of 27 ships for a total of of Allied shipping. Merten joined the Reichsmarine (navy of the Weimar Republic) in 1926. He served on the light cruisers Karlsruhe and Leipzig during the Spanish Civil War patrols.
At the outbreak of World War II, he was stationed on the battleship , participating in the Battle of Westerplatte and Battle of Hel. He transferred to the U-boat Arm in 1940, at first serving as a watch officer on before taking command of U-68 in early 1941. Commanding U-68 on five war patrols, patrolling in the Atlantic Ocean, the Caribbean Sea and the Indian Ocean, he was awarded Knight's Cross of the Iron Cross on 13 June 1942 and the Oak Leaves to his Knight's Cross on 16 November 1942. On the second patrol, Merten helped rescue the crews of the auxiliary cruiser Atlantis and the refuelling ship Python, which had been sunk by the Royal Navy. In January 1943 Merten became the commander of the 26th U-boat Flotilla and in March 1943, Merten was given command of the 24th U-boat Flotilla. In February 1945, he was posted to the Führer Headquarters in Berlin. At the end of the war, he was taken prisoner of war by US forces and released again in late June 1945.
After the war, Merten worked in salvaging sunken ships in the Rhine river. In November 1948, Merten was arrested by the French and accused of allegedly wrongful sinking of the French tanker Frimaire in June 1942. He was acquitted and later worked in the shipbuilding industry. Merten, who had written his memoir and books on U-boat warfare, died of cancer on 2 May 1993 in Waldshut-Tiengen, Germany.
Early life and career Merten was born on 15 August 1905 in Posen, in the Prussian Province of Posen in the German Empire, present-day Poznań, Poland. His father was Dr. jur. Karl-Friedrich Merten, who in 1910 became the mayor of Elbing, present day Elbląg. In 1934, he was forced out of office when he refused to join the Nazi Party. Merten had a sister and a brother, both died before he had turned seven. His younger brother Klaus, as a Feldwebel (staff sergeant) in a pioneer platoon, died in 1942 of wounds sustained on the Eastern Front. Aged thirteen, Merten joined the Königliches Preußisches Kadettenhaus (Royal Prussian Cadet House) in Köslin, present-day Koszalin, on 1 April 1918. Following World War I, the cadet house was transformed into a state-run boarding school. There, he attended the school from 1920–26 and graduated with his Abitur (university entry qualification) on 20 March 1926.
He joined the Reichsmarine on 1 April 1926 as a member of "Crew 26" (the incoming class of 1926). He underwent basic military training with the 5th company of the 2nd department of the standing ship division of the Baltic Sea on the Dänholm in Stralsund.5th company—5. Kompanie2nd battalion—II. Abteilungstanding ship division—Schiffsstammdivision Merten was then transferred to the training ship Niobe (12 July – 17 October 1926), attaining the rank of Seekadett (officer cadet) on 12 October 1926. Following a 17-month stay on board the cruiser Emden (18 October 1926 – 24 March 1928), he advanced in rank to Fähnrich zur See (midshipman) on 1 April 1928.
Merten sailed on Emdens first training cruise, which began on 14 November 1926 and started in Wilhelmshaven. The journey took him and her crew around Africa to Indonesia and the Cocos Islands where was lost on 9 November 1914. There the crew held a commemoration on 15 March 1927. The journey then continued to Japan and Alaska down the west coast of North and South America, around Cape Horn. They celebrated Christmas and New Year's Day in Rio de Janeiro. From there they headed to Middle America and the Azores. Their final stopover was Vilagarcía de Arousa, Spain before they returned home on 14 March 1928.
Following his journey on Emden, Merten attended the main cadet course at the Naval Academy at Mürwik (25 March 1928 – 22 March 1929).main cadet course—Hauptlehrgang für Fähnriche This course was briefly interrupted for two navigational training courses, the first on the tender Nordsee (9–13 July 1928) and the second on the survey vessel Meteor (8–13 October 1928). He then underwent a number of specialized training courses which included a torpedo course in Mürwik (23 March – 1 June 1929),torpedo course for cadets—Torpedolehrgang für Fähnriche a communication course for cadets at Mürwik again (2 June – 6 July 1929),communication course for cadets—Nachrichtenlehrgang für Fähnriche a pathfinder course for cadets at Kiel (7 July – 4 August 1929),mine warfare course for cadets—Sperrlehrgang für Fähnriche a naval infantry course for cadets with the 8th company of the 2nd battalion of the standing ship division at Stralsund (5 August – 27 October 1929),infantry course for cadets—Infanterielehrgang für Fähnriche and lastly an artillery course for cadets at Kiel-Wik (28 October 1929 – 2 February 1930).artillery course for cadets—Artillerielehrgang für Fähnriche Merten was then transferred to the battleship (3–24 February 1930) and (25 February – 22 September 1930) for further ship based training. On this assignment, he was promoted to Oberfähnrich zur See (Ensign) on 1 June 1930. His cadet mentor on Elsass and Schleswig-Holstein was Korvettenkapitän (Corvette Captain) Ernst Lindemann.cadet mentor—Fähnrichsvater Lindemann later commanded the battleship Bismarck. Merten's next service position was a gunnery officer on the light cruiser Königsberg (23 September 1930 – 23 September 1931). There he was made an officer, attaining the rank Leutnant zur See (acting sub-lieutenant) on 1 October 1930. His stay on Königsberg was briefly interrupted for a gas protection course (6–16 January 1931).gas protection course—Gasschutzlehrgang
For two years, Merten then became gunnery instructor at the Naval Artillery School in Kiel-Wik (24 September 1931 – 29 September 1933). During this timeframe, Merten himself attended an anti-aircraft artillery course at Wilhelmshaven (16 February – 12 May 1932),anti-aircraft artillery course—Fla-Waffenlehrgang and an anti-aircraft artillery instructors course in Wilhelmshaven and on the tender Fuchs (11 October – 14 December 1932). On 15 December 1932, Merten was posted to the gunnery training ship , serving as 2nd artillery officer. After this assignment, which ended on 25 March 1933, he was promoted to Oberleutnant zur See (lieutenant (junior grade)) on 1 April 1933. In 1933, Merten first met his future wife, Ruth Oldenburg from Wiesbaden. At the time, she was a first semester medicine student at the University of Kiel. On 15 March 1934, the marriage approval was granted by Naval Personnel Office.Naval Personnel Office—Marineleitung/Marine-Personalamt The two married on 21 April 1934 in Wiesbaden. The marriage resulted in the birth of a daughter, Karen-Helge, born on 11 June 1935, a son Karl-Friedrich Birger, born 15 March 1939, and another son, Jan, born February 1947.
For the next five months (30 September 1933 – 26 February 1934), Merten served as the artillery referent with the Commander of Minesweepers (F.d.M.).Commander of Minesweepers—Führer der Minensuchboote In parallel to this assignment, he served as 2nd watch officer on the torpedo boat T-156 in the 2nd Minesweeper-Demi-Flotilla as well as Flag Lieutenant with the Commander of Scouting Forces (B.d.A.) on the fleet tender Hella (6–29 January 1934).2nd Minesweeper-Demi-Flotilla—2. MinensuchhalbflottilleCommander of Scouting Forces—Befehlshaber der Aufklärungsstreitkräfte He then posted to the anti-artillery training course at the Naval Coast Artillery School in Wilhelmshaven (27 February – 28 March 1934). He then transferred back to his former position of 2nd watch officer on torpedo boat T-156 (29 March – 30 September 1934), this posting was briefly interrupted by a transfer to the light cruiser Königsberg (8 July – 2 August 1934).
Merten was posted to the light cruiser Karlsruhe (21 September 1935 – 7 March 1937), serving as the 2nd artillery officer and watch officer. On 1 April 1936, Merten was promoted to Kapitänleutnant (captain lieutenant) and on 2 October 1936 received the Wehrmacht Long Service Award 4th Class, which had been created on 16 March 1936, for four years of military service. In back-to-back assignments, he was briefly transferred to the light cruiser Leipzig (8 March – 20 May 1937), serving as the anti-aircraft artillery officer, and then again on Karlsruhe (21 May – 11 June 1937). On Karlsruhe and Leipzig he participated in the Kriegsmarines non-intervention patrols of the Spanish Civil War. For this service he received the Spanish Cross in Bronze on 20 April 1938. Merten led a Star sailing boat training course (21 July – 29 September 1937) and was then given command of the escort ship F-7 (30 September 1937 – 12 February 1939).
World War II From 1 March to 30 June 1939, Merten took an artillery officer's training course for battleship and was posted to Schleswig-Holstein in July 1939 as a cadet training officer. World War II began on 1 September 1939 when German forces invaded Poland. Merten participated in the bombardment of the Polish base at Danzig's Westerplatte in the early morning hours of 1 September 1939. On 7 September, he led Schleswig-Holstein's naval infantry troops in the Battle of Hel. Together with the 5. Marineartillerie-Abteilung (5th Naval Artillery Department), German troops landed on the Hel Peninsula. For his actions in these battles he received the Iron Cross 2nd Class () on 2 October 1939.
Merten volunteered for service with the U-boat arm in 1940. He attended his first U-boat training course with the torpedo school in Flensburg-Mürwik (29 April– 2 June 1940), followed by another course at the communications school, also in Flensburg-Mürwik (3–30 June 1940). He was then posted to the 1st U-boat Training Division (1 July – 29 September 1940), followed by a U-boat commander's course with the 24th U-boat Flotilla (30 September – 29 November 1940). On 30 November 1940, Merten was transferred to the 2nd U-boat Flotilla, joining the crew of Kapitänleutnant Heinrich Liebe's as a commander in training and watch officer. Merten went on one war patrol with U-38 (18 December 1940 – 22 January 1941). This was Liebe's eighth war patrol as a commander, during which two ships of were sunk.
U-boat commander and first patrol On 24 January 1941, Merten was stationed at the DeSchiMAG AG Weser shipyard in Bremen, for familiarization with . U-68 was a Type IXC U-boat, designed as a large ocean-going submarine for sustained operations far from the home support facilities. Merten commissioned U-68 on 11 February 1941 into the 2nd U-boat Flotilla. He took U-68 on five war patrols, patrolling in the Atlantic Ocean, the Caribbean Sea and the Indian Ocean. He surrendered command of U-68 on 18 January 1943 to Oberleutnant zur See Albert Lauzemis.
Merten's first patrol (30 June – 1 August 1941) was a transfer patrol into the northern Atlantic Ocean, taking U-68 from Kiel to Lorient in France. The patrol, taking U-68 into the North Atlantic, lasted 33 days and covered afloat and submerged. His 1st watch officer on this patrol was Oberleutnant zur See August Maus, 2nd watch officer was Lauzemis. Merten did not sink any ships on this patrol.