Following the Boer declaration of independence for the Transvaal in 1880 the British suffered a series of disastrous defeats in attempting to regain the territory. At the outbreak of the war Elwes shipped out to South Africa where he was seconded from the 3rd Battalion, Grenadier Guards to the 58th Regiment and appointed Aide-de-Camp to Major-General Sir George Pomeroy Colley, then the British High Commissioner for South East Africa and Commander-in-Chief of Natal. On 9 January 1881 Elwes dined at Government House at Pietermaritzburg with Colley, his wife, Lady Colley, and other officers and members of the general's staff. Guests included the author H. Rider Haggard. The next day Elwes left Pietermaritzburg with the British Natal Field Force led by Colley who took them into the Transvaal via Newcastle and Laing's Nek to Pretoria to relieve the garrisons in the besieged towns who were desperately short of food and ammunition.