British encroachment into areas of South Africa already settled by the Afrikaner Boers and the competition for resources and land that developed between them as a result , led to the Second Boer War in 1899 . Pre @-@ empting the deployment of British forces , the Afrikaner Republics of the Orange Free State and the Transvaal Republic under President Paul Kruger declared war on 11 October 1899 , striking deep into the British territories of Natal and the Cape Colony . After the outbreak of war , plans for the dispatch of a combined Australian force were subsequently set aside by the British War Office and each of the six colonial governments sent separate contingents to serve with British formations , with two squadrons each of 125 men from New South Wales and Victoria , and one each from the other colonies . The first troops arrived three weeks later , with the New South Wales Lancers — who had been training in England before the war , hurriedly diverted to South Africa . On 22 November , the Lancers came under fire for the first time near Belmont , and they subsequently forced their attackers to withdraw after inflicting significant casualties on them .