Stewart followed his father into the army and was commissioned with the
Gordon Highlanders. He served in
India and between 1879 and 1880 took part in the
Second Anglo-Afghan War, during which he was severely injured. He went on to serve in the
First Boer War in 1881 and the
Mahdist War between 1884 and 1885. He left the army in 1888. He remained on the Gold Coast until August 1904, when he was made
Commissioner of the
East Africa Protectorate. At the beginning of his term he was involved in discussions with the
Maasai over land rights and signed the
First Maasai Treaty in 1904. His tenure, however, was short-lived and he died while in
Nairobi from
pneumonia on 1 October 1905. He is buried at
Nairobi South General Cemetery. ==Personal life==