Wood was on the staff of Lieutenant-General Thesiger (who later became Lord Chelmsford), who was then in command of a column in Natal in the Xhosa Wars (also known as the Cape Frontier Wars). He was employed as a field officer of the 90th Light Infantry, which had arrived in South Africa in January 1878, in the last battle of the wars at Tutu Bush (May 1878). On 13 November he was promoted to the substantive rank of lieutenant-colonel, and on the same day he was appointed commanding officer of the 90th Light.