Commissioned into the Prussian navy in 1857, Valois fought at the Battle of Jasmund in 1864. Between 1865 and 1868 he circumnavigated the world and later served in the Franco-Prussian War as captain of . He sank or captured several French ships before being blockaded in Vigo until the end of the war. In 1890 he became commander of the German East Asia Squadron. Towards the end of his naval career and in retirement he was active in the debate regarding the role of the German navy. Valois supported creating a fleet of light commerce raiders, as opposed to the orthodoxy of building up a battleship force for a decisive fleet action. He wrote several influential books and pamphlets.