Among the reasons for the South African War (Anglo- Boer War), 1899 - 1902, was that the Afrikaners attempted to assert their independence as a nation in the face of British Imperialism. This was complicated by the discovery of diamonds in Kimberley and gold on the Rand. Also, South Africa was a British colony at the time, and thus the Empire did not look too kindly on the aspirations of their colony for independence, particularly with the discovery of such mineral wealth. British attempts to crush these aspirations were however quite difficult. The settlers were determined, were quite able to survive in the African climate and were well armed. The settlers were also very skilled at guerrilla warfare, introducing the world to the concept of a' Kommando' unit, while the British army was large and more suited to battles fought on the European mainland. For a while the Boer Republics were able to hold their own against the British army as their hit and run tactics took a considerable toll on the British.     The Battle of Vaalkrans on the 5th of February 1900 was a minor battle in which the British sought to avenge their defeat at The Battle of Spionkop. However victory continued to elude them, as they were forced to eventually withdraw from this particular engagement. The British won the war as they employed scorched earth tactics, had a larger army and the very latest in equipment of the time. 
References

Evans.M.M, (1999) The Boer War: South Africa 1899-1902, (Great Britain: Osprey Publishing)