 He was promoted to lieutenant in 1905 and assigned to the battleship "Chin'en", followed by the cruisers in 1906 and (where he was chief gunnery officer) in 1907.Matsudaira was promoted to lieutenant commander in 1910, which was also the same year that he succeeded to the head of the Aizu Matsudaira household.He inherited his brother's title of viscount ("shishaku") under the "kazoku" peerage system.