A number of interrelated factors led to the Second Anglo-Boer War. These include the conflicting political ideologies of imperialism and republicanism, the discovery of gold on the Witwatersrand, tension between political leaders, the Jameson Raid and the Uitlander franchise. On 9 October 1899 the South African Republic issued an ultimatum to Britain and two days later, on 11 October war was officially declared between Britain and the Boers. The British forces thought that the war would be won easily, but they were wrong. The two Boer republics that were involved in the conflict were the Transvaal and the Orange Free State Republics. In the encyclopaedia the 'New History of South Africa' (2007) the authors claim that the South African War (Second Anglo-Boer War) of 1899-1902 remains the most ter­rible and destructive modern armed conflict South Africa has experienced. Its shock waves continued to be felt long after the conclusion of peace in May 1902, and it remains a powerful event in shaping the history of twentieth-century South Africa. One way to understand its significance is to view it, as some historians have done, as a conflict that was as important in the making of modern South Africa as the American Civil War was in the history of the United States. Related: The South African War 
References

Wallis, F. (2000). Nuusdagboek: feite en fratse oor 1000 jaar, Kaapstad: Human & Rousseau.|

South African History Online,'South African War 1899-1902 Second Anglo-Boer War',From South African History Online,[Online],Available at: www.sahistory.org.za,[Accessed: 02 October 2013]