Posted again to South Africa in September 1899, on the outbreak of the Second Boer War, he raised and commanded Bethune's Mounted Infantry, receiving the rank of lieutenant colonel on 29 September 1900. His unit fought at the battles of Colenso and Spion Kop, and took part in the relief of Ladysmith. In late 1900 he was recalled to the 16th Lancers as a brevet colonel, becoming their commanding officer and heading a cavalry brigade. Then he was moved to staff work, acting as Assistant Adjutant-General of the Field Force in South Africa. He was mentioned in despatches three times (including in the final despatch by Lord Kitchener dated 23 June 1902).