Stewart was born the son of Robert Stewart and Flora Stewart (née Martin) at Mount Pleasant, near Forres, Moray in Scotland. Both parents were from Highland families. His father represented a branch of the Stewarts of Fincastle, descendants of King Robert II of Scotland. His mother was a daughter of Rev. Donald Martin, Minister of Abernethy, in Strathspey, but originally from Skye, and connected to the clans on that island.[2] Young Donald was educated at schools at Findhorn, Dufftown and Elgin and at the University of Aberdeen.[1][3]
During the Indian Rebellion, after a famous ride from Agra to Delhi with dispatches, Stewart served as the deputy assistant adjutant-general at the Siege of Delhi in Summer 1857 and then as assistant adjutant-general at the Siege of Lucknow in Autumn 1857.[5] After serving through the campaign in Rohilkhand he was promoted to major on 19 January 1858[6] and to lieutenant-colonel on 20 July 1858.[5] He became deputy-adjutant-general of the Bengal Army in 1862 and, having been promoted to colonel on 20 July 1863,[7] he commanded the Bengal brigade in the Abyssinian expedition in 1867.[5] Promoted to major-general on 24 December 1868,[8] he became commandant of the penal settlement of the Andaman Islands, and was present when one of the inmates assassinated Lord Mayo, British Viceroy of India, in 1872.[1][9] After being exonerated in the subsequent inquiry, he was appointed Commander of the troops at Lahore in 1876.[9]
Major-General Sir Norman Robert Stewart, 2nd Baronet, CB (1851–1926), Indian Army; married 1875 Adeline Hewett, of Bombay; and left issue a son and two daughters.
Flora Alice Stewart (b.1853); married 1st 1877 Brigadier-Surgeon Richard William Davies (d. 1890); married 2nd 1893 Major Sir Walter Kentish William Jenner, 2nd Baronet (1860–1948); left children.
Marina Annie Stewart (b.1855); married 1882 Major-General Sir Francis John William Eustace, KCB.
Sir Donald William Stewart, KCMG, (1860–1905), a military officer and Commissioner of the East Africa Protectorate.
Norah Helen Gertrude Stewart (b.1868); married 1st 1891 (div. 1894) S. J. O′Neill Murphy; 2nd 1899 Captain Leopold Christian Duncan Jenner; and had issue by first marriage.