Born 2. Sept. 1852 in Kopenhagen, his father Karl Rosendahl was clerk in the finance ministry of Denmark. His mother was Ida Paulsen. Entered the German navy as midshipman in 1869, became sub-lieutenant in 1873, lieutenant in 1876, lieutenant-commander in 1883, Korvettenkapitän on 15.4.1890. He was commander of the II. Torpedodepartment from May 1891 until Sept. 1894. Commander of  the coast-armoured-ship SMS “Hagen” from Oct. 1894 until Sept. 1895, of SMS “Friedrich Carl” from Sept. 1895 until January 1898. During that period he was appointed captain in 1896. Was then appointed as the first governor of Jiaozhou Leased Territory and arrived in Tsingtau, together with his wife and small daughter, on April 15 th,1898. But Tirpitz was dissatisfied with Rosendahl’s handling of his task in Tsingtau, so already on October 10^th, 1898 Tirpitz appointed captain Paul Jaeschke as new governor. But Rosendahl had to stay in Tsingtau until February 1899, because Jaeschke arrived there only on Febr. 18^th, 1899. In February 1899 Rosendahl returned to Germany and again became commander of a warship, this time it was the battleship (Linienschiff) “Brandenburg”. He started his command in Sept. 1899. When the Boxer Rebellion started in China, the German government sent in July 1900 several warships from Germany to China, among them also the SMS “Brandenburg”. Therefore Rosendahl came back to China in 1900-01, also visited Tsingtau with his ship. For instance he was in Tsingtau on April 8 th 1901 and attended the inauguration ceremony for the opening of the railway line from Tsingtau to the city of Jiaozhou. In August 1901 he was again here, but only for one day to say “Good bye”, and then returned to Germany, where he arrived in September 1901. There he was pensioned on     January 11 th,1902 with the title of rear-admiral. In February 1904 the construction of the railway line from Tsingtau to Tsinan was finished. On February 23 rd 1904 the first train from Tsingtau reached Tsinan, the locomotive had the name “Rosendahl”. – He died in Trient on August 11^th,1917.