Bavarian-born Vice Admiral who succeeded Paul Behncke as the State Secretary of the Imperial Naval Office. He entered the Navy in 1884, reaching the rank of Korvettenkapitän by September 1909. His chief assignment at the time was escorting Kaiser Wilhelm II's yacht, the Hohenzollern. He then served for two years as commander of the cruiser Friedrich Carl. From September 1911 until January 1913, he commanded the cruiser Von Moltke, and thereafter commanded the destroyer Kaiser until September 1913.

As Germany mobilized for war, Ritter von Mann was the Fleet Chief of Staff. He spent most of the war, until December 1917, as Chief Inspector of Torpedo Technology. At that point, he was selected to head up the fledgling U-Boot office at Imperial Naval Headquarters, and while there was promoted to Vice-Admiral. In October 1918, he succeeded Paul von Behncke as State Secretary for the Imperial Navy. In November, Ritter von Mann selected U-Boot commanders loyal to the Kaiser to search for and destroy destroyers which the mutinous sailors in Kiel had taken over. He also unsuccessfully sought from the Cabinet to bombard Kiel from the sea and land. Von Mann left office on 13 February 1919 and went into retirement. He died on 2 October 1934 in Bad Reichenhall, his native Bavaria.