 In 1914, he was appointed chief gunnery officer on the battleship , and served from 1915-1916 as executive officer on the cruiser .Matsudaira was promoted to commander in 1916, and was assigned as aide-de-camp to Prince Fushimi Hiroyasu from December 1916-November 1918.On 10 November 1918, he was reassigned as executive officer on the battleship .