He was educated at Harrow School and Royal Military College, Sandhurst, before being commissioned into the 108th (Madras Infantry) Regiment of Foot in January 1868.
He served in the Second Anglo-Afghan War in 1879, and in Burma, 1885–1889, being mentioned in despatches (dated 2 September 1887) and awarded the Distinguished Service Order (DSO).
[1][2] Elliott participated in the Dongola Expedition of 1896, when he was again mentioned in despatches and after it was appointed a Companion of the Order of the Bath.
During the latter part of the war he commanded troops in the east of the Orange River Colony, and following the announcement of peace on 31 May 1902, he supervised the surrender of arms in that area.
Following the end of the second Boer war, Elliot returned home to the United Kingdom, but in late 1902 was back in India to take up his former employment as Inspector General of Cavalry.