Otto Hersing (30 November 1885 – 1 July 1960) was a German naval officer who served as U-boat commander in the Kaiserliche Marine and the k.u.k. Kriegsmarine during World War I. In September 1914, while in command of the German U-21 submarine, he became famous for the first sinking of an enemy ship by a self-propelled locomotive torpedo. Career Early life and training Hersing joined the Imperial German Navy in 1903. He received his first training on the school ship Stosch, on the corvette Blücher and on the artillery training ship Mars. He served as a Fähnrich on the battleship Kaiser Wilhelm II. In September 1906 he was promoted to Leutnant and transferred on the light cruiser Hamburg. On 1909, he was promoted to Oberleutnant. From 1911 to 1913, Hersing served as watch officer on the protected cruiser Hertha, and he had the chance to sail around the Mediterranean Sea and the West Indies. World War I and North Sea operations In 1914, Hersing was promoted to Kapitänleutnant and received special training for the submarine warfare. When World War I broke out, he was given command of U-21, at the time located at the island of Heligoland in the North Sea. Between August and September, U-21 carried out reconnaissance in the North Sea, but he was not able to find any enemy ships. Hersing then tried to force his way into the Firth of Forth, at that time a British naval base, but with no success. On September 5, Hersing spotted the light cruiser Pathfinder off the Scottish coast, sailing at a reduced speed of 5 knots due to a shortage of coal. Hersing decided to attack the ship and hit her with a single torpedo just below the bridge, close to the ship's powder magazine, which was destroyed by a great explosion. The ship sank in a short time, and 261 sailors were killed. It was the first sinking of a modern warship by a submarine armed with torpedoes. On 14 November, U-21 intercepted the French steamer Malachite. Hersing ordered the crew to abandon the ship before he sank the vessel with his deck gun. Three days later, the British collier Primo suffered the same fate. These two ships were the first vessels to be sunk in the restricted German submarine offensive against British and French merchant shipping. At the beginning of 1915, Hersing received the Iron Cross, 2nd