Born at Auchterblair, near Carrbridge, Inverness-shire, Grant was the second son of Major John Grant of the 97th Regiment of Foot and Anna Trapaud Grant.[1] He joined the Bengal Native Infantry as an ensign on 16 July 1820 and was promoted to lieutenant on 11 July 1823 and to captain on 14 May 1832.[1] He became a brigade major in Oudh in 1834 and, having raised the Hariana Light Infantry in 1836, he became second assistant in the adjutant-general's department of the Bengal Presidency in 1838.[1]
When General George Anson died of cholera on his march against the mutineers in May 1857, Grant, as senior commander in India, was summoned to Calcutta to become acting Commander-in-Chief, India.[5] From Calcutta he directed the operations against the mutineers, sending forces under Henry Havelock and James Outram for the relief of Cawnpore and Lucknow.[5] Although the Viceroy of India, Lord Canning, had recommended that Grant be confirmed in the role of commander-in-chief, Sir Colin Campbell had already been nominated as Anson's successor.[5] So on the arrival of Campbell from England in August 1857, Grant returned to command the Madras Army again.[5]
Grant returned to England in January 1861 and was promoted to the substantive rank of colonel on 14 November 1861[9] and to lieutenant-general on 24 October 1862.[10] In February 1864 he was appointed to a Royal Commission formed to inquire into the best mode of realizing the value of booty of war.[11] He became Governor of Malta in 1867 and was promoted to full general on 19 November 1870.[12]
In 1832, Grant married Jane Anne Fraser-Tytler, daughter of William Fraser-Tytler; they had two sons.[1] Following the death of his first wife, he married secondly the Hon. Frances Maria Gough, daughter of Field Marshal Hugh Gough, 1st Viscount Gough, in 1844; they had five children (four sons, including Sir Henry, and a daughter Frances).[24]