From soon after its acquisition by Britain during the Napoleonic wars, the southern tip of Africa had been shared between British colonies and independent republics of Dutch–Afrikaner settlers, known as Boers. In order to escape British rule many Boers had moved north and east to settle on new lands which eventually became the Boer republics of the Orange Free State and the Transvaal. The relationship between the British and the Boers was an uneasy one, with Britain extending its control by annexing Natal in 1845, although London did recognise the two republics in two treaties in the 1850s. Throughout the nineteenth century tensions were often high, and in 1880–81 the two sides fought a war in which the Boers inflicted several costly defeats on the British army. Coupled with the advent of a new government in London reluctant to fight the war, this ensured that the Transvaal was able effectively to maintain its independence.
The discovery of gold and diamonds in the Boer republics in the 1880s further intensified the rivalry, particularly as British subjects flooded into the Boer territories in search of wealth. The rights of British subjects in Boer territory, British imperial ambition, and the Boer desire for to stay outside the British Empire all caused more friction, which in 1899 provoked the Boers to attack in order to forestall what they saw as an impending British conquest.
As part of the British Empire, the Australian colonies offered troops for the war in South Africa. Australians served in contingents raised by the six colonies or, from 1901, by the new Australian Commonwealth. For a variety of reasons many Australians also joined British or South African colonial units in South Africa: some were already in South Africa when the war broke out; others either made their own way or joined local units after their enlistment in an Australian contingent ended. Recruiting was also done in Australia for units which already existed in South Africa, such as the Scottish Horse.
Australians served mostly in mounted units formed in each colony before despatch, or in South Africa itself. The Australian contribution took the form of five waves. The first were the contingents raised by the Australian colonies in response to the outbreak of war in 1899, which often drew heavily on the men in the militia of the colonial forces. The second were the bushmen contingents, which were recruited from more diverse sources and paid for by public subscription or the military philanthropy of wealthy individuals. The third were the imperial bushmen contingents, which were raised in ways similar to the preceding contingents, but paid for by the imperial government in London. Then were then the draft contingents, which were raised by the state governments after Federation on behalf of the new Commonwealth Government, which was as yet unable to do so. Finally, after Federation, and close to the end of the war, the Australian Commonwealth Horse contingents were raised by the new federal government. These contingents fought in both the British counter-offensive of 1900, which resulted in the capture of the Boer capitals, and in the long, weary guerrilla phases of the war which lasted until 1902. Colonial troops were valued for their ability to shoot and ride, and in many ways performed well in the open war on the veldt. There were significant problems, however, with the relatively poor training of Australian officers, with contingents generally arriving without having undergone much training and being sent on campaign immediately. These and other problems faced many of the hastily raised contingents sent from around the empire, however, and were by no means restricted to those from Australia.
The Australians at home initially supported the war, but became disenchanted as the conflict dragged on, especially as the effects on Boer civilians became known.