With the outbreak of the Second Boer War, Elliott volunteered for service, and was utilised as a medic attached to No.4 field Hospital. He was present at both the Battle of Spion Kop and Battle of Vaal Krantz and aftwards was posted at Ladysmith. He was made Civil Surgeon-in-charge of the 4th Brigade, in medical charge of the 21st, 42nd and 53rd Batteries of the Royal Artillery. He held this role until his death from fever on 1 December 1900 at Middelburg, Transvaal.