His U-boat was decorated with a horseshoe symbol on the conning tower and he was very lucky indeed. In one month in 1941 three top submarine commanders were put out of action by the British. On 17 March 1941, in the North Atlantic, Kretschmer's vessel was caught by HMS Walker and badly damaged. Kretschmer was able to scuttle his submarine and lead most of the crew into captivity. Two other submarine "aces" were not so lucky. Joachim Schepke lost his life on the U-100. Gunther Prien, who had sunk the battleship HMS Royal Oak at Scapa Flow on 14 October 1939 with a loss of 883 British lives, went to the bottom in the U-47.
Born in 1912, the son of a schoolteacher, Kretschmer sought a career in the small navy of the Weimar Republic in 1930. Although the navy was expanding slowly, and was involved in secret deals with the Soviet fleet, promotion was expected to be slow. In January 1932, with the rank of petty officer, Kretschmer was sent to serve in the pocket battleship Deutschland and the cruiser Emden. As an officer he joined the submarine service in 1934.
The 1935 naval agreement with Britain gave Hitler's Reichsmarine the prospect of more rapid expansion and the submarine service was given due attention. Kretschmer spent the remainder of the pre- war years serving with the German naval patrol protecting Franco's interests during the Spanish Civil War.
After sinking many merchant ships Kretschmer sank HMS Daring, a destroyer, off Norway on 18 February 1940. Thus he joined the select band of officers who had sunk an enemy warship. His war looked like being a good one.
Kretschmer was a tall, polite man of gentle formality. He was known as a disciplinarian who punished his men for being drunk on leave. He was highly skilled and courageous and suffered with his men the cold, cramped conditions and poor diet of the submariners. Yet in the month when Kretschmer nearly lost his life attempting to sink almost defenceless merchant ships, Hermann Goering, second man in Hitler's Reich, was busy looting the art treasures of Paris for his own collection.
No doubt highly frustrated at being captured, Kretschmer carried on the war from his prisoner-of-war camp in Canada. He organised a two-way radio link to the German Naval High Command. A mass breakout was put in motion with a German submarine waiting as arranged at the St Lawrence River to pick up the prized submarine commanders. The plot was foiled by the Canadians at the last minute.
In another incident, a German officer in the camp was ostracised for allegedly surrendering his submarine to the British. He argued that he had done so in order to save the lives of his men. He was threatened with a so-called "honour court" headed by Kretschmer and had to be relocated by the camp authorities. Kretschmer was returned to Germany in 1947. He was one of the handful of U-boat commanders to have survived.
Kretschmer answered the call for volunteers in 1955 when the Bundesmarine (Federal Navy) was established. It was more like the navy he joined in 1930 than the navy he saw disbanded in 1945. The new force was seen largely as coastal defence. By 1965 it remained smaller than the Swedish navy, being made up largely of destroyers borrowed from the US and smaller vessels. The submarine arm consisted of only five craft as against 26 Swedish submarines.
The Bundesmarine was different in other ways too. It could not get the recruits it wanted. In 1934, the German navy had been able to reject 9 out of 10 officer applicants; in 1964 the Federal Navy accepted 60 per cent. Kretschmer and the other veterans had also to come to terms with the concept of servicemen as citizens in uniform. Many found this difficult. Flotillenadmiral (Admiral) Heinrich Gerlach, head of training, got into difficulties over his opinion that despite mistakes "much was excellent" in the Third Reich. On the other hand, Admiral Helmut Heye, responsible for ensuring servicemen were not abused, caused equal controversy when he attacked dangerous tendencies in the armed forces in 1965.
In that year Kretschmer was promoted to Flotillenadmiral and he also served as Chief of Staff, Allied Naval Forces Nato Baltic Approaches. One of his last sad duties was to conduct an inquiry into the loss of the 232-ton submarine Hai with loss of 19 lives in September 1966. It had been heading for Scotland on a goodwill mission. Hai, a wartime U- boat, had been scuttled in 1945, salvaged and recommissioned 11 years later. Kretschmer found considerable technical faults and deficiencies in the training and command of the crew. The report did not gain him friends at the top levels of the navy.
Kretschmer finally took off his uniform for good in 1970. West Germany had a new government, and the Social Democrat Helmut Schmidt, himself a wartime artillery officer, was the new Defence Minister. He wanted younger men in the highest ranks of the armed forces.
In retirement Kretschmer retained his interest in all things naval and was happy to discuss the war with historians, former foes and more recent allies.
Otto Wilhelm August Kretschmer, naval officer: born Heldau, Silesia 1 May 1912; married 1948 Dr Luise-Charlotte Mohnsen-Hinrichs (nee Bruns); died Straubing, Germany 5 August 1998.