In 1886, as
midshipmen, Cowan and Beatty joined ,
flagship of the
Mediterranean Fleet. Cowan saw service in
Benin and
Nigeria in 1887. He later took command of the destroyer and acted as second-in-command of the
Devonport destroyer flotilla under
Roger Keyes, who was then developing new destroyer tactics. They became firm friends. Cowan commanded several more destroyers, acquiring a widespread reputation as a destroyer captain, and then succeeded Keyes in command of the flotilla. In 1904 he was appointed
Member of the Royal Victorian Order. In 1905 he took command of and he was promoted
captain in 1906. He transferred to the
cruiser in 1907. In 1908, he took command of all destroyers of the
Channel Fleet. In 1909, he transferred to the Third Division of the Home Fleet with command of the nucleus-crewed , and in 1910 he became captain of the new light cruiser . In 1912, Cowan became Assistant to
John de Robeck, who was then Admiral of Patrols. ==First World War==