The simmering conflict between British imperial expansion and Boer independence erupted into war in October 1899. The first shots were fired on 12 October at Kraaipan in North West when a commando under J.H. (Koos) de la Rey derailed and then captured a British armoured train. Boer forces from the South African Republic (ZAR) and Orange Free State outnumbered and outmaneuvered the garrisons in the Cape and Natal colonies and besieged them in the border towns of Mafikeng, Kimberley and Ladysmith. In November, three regiments of baKgatla ga ba Kafela, under British command, retaliated and destroyed a Boer laager at Derdepoort. Initial attempts to relieve the sieges resulted in spectacular British defeats, but the static nature of siege warfare ultimately favoured the British. Field-Marshall Lord Roberts was recalled from retirement to lead the British forces which were pouring into South Africa from all over the Empire. The vast numbers turned the tide against the Boers who were relentlessly pushed back into their home territories during the first half of 1900. By June, the capitals of both republics had fallen and demoralized Boers drifted back to their farms under oath of neutrality. For most people the war appeared to be over.
However, at this critical moment, Boer leadership shifted away from the conservative old guard and generals with more innovative ideas took command. Each operated autonomously in different parts of the country, restoring morale and establishing smaller, highly mobile commandos more adapted to guerrilla raids than to large-scale conventional battles. The north-western region fell under De la Rey. Within a month of the fall of Pretoria he and his subordinate combat generals succeeded in re-recruiting a substantial fighting army. Rustenburg was invested and isolated through vigorous skirmishes in the Magaliesberg. Boer resolve to persist with the war was further strengthened by a meeting between Presidents Steyn of the Orange Free State and Kruger of the Transvaal. Steyn had reached Kruger after he and his army chief, General Christiaan de Wet, had eluded pursuit by overwhelming British forces through the north-west areas.
As Boer resistance continued, the British also restructured the army into columns of mobile mounted infantry. They also introduced the systematic destruction of Boer farms. Farm-burning had been advocated by Lord Roberts as a punitive measure against Boers who broke their oath of neutrality. His successor, Lord Kitchener, extended it to include the destruction of all farms, including all crops and livestock that might offer sustenance to the wandering commandos. Refugee (concentration) camps were established to accommodate displaced non-combatants. Farmlands in what is today the North West Province were among the most severely affected by this scorched earth policy. With it came a growing imperative for the Boers to find alternative sources of survival. Guerrilla attacks began to focus less on disrupting enemy activity and more on capturing supplies and looting became more important than maximizing the military victory. The battles of Buffelspoort and Nooitgedacht in the Magaliesberg in December 1900 were examples of this. In addition, farm-burning was occasionally exacerbated by Boers retaliating by destroying the farms of countrymen who had not taken up arms again.
In 1901 the British introduced a new strategy. Blockhouse lines consisting of small iron and masonry forts linked by barbed wire were erected across the landscape to safeguard supply lines and surround the mobile commandos. By the end of that year, the network of enclosures extended from Klerksdorp to Johannesburg and north to the Magaliesberg. At the end of the war, it stretched to the Bechuanaland (Botswana) border at Mafikeng. Within these vast corrals, mounted infantry spread out to trap the commandos and, although initially ridiculed by the Boers, the system hampered their movements and contributed to their defeat.
North of the Magaliesberg and Dwarsberg Boer movement was further curtailed by baKgatla bands that occupied the vacated farms and occasionally attacked the displaced women and labourers who were avoiding internment in the concentration camps. A further contributor to the eventual Boer defeat was the loss of their horses. Their fighting ability depended entirely on their mobility and skill as horsemen but from 1901 African horse-sickness spread rapidly. Hundreds of horses died, leaving their owners as burdens to their mounted comrades.
The war ended in May 1902 but its legacy of bitterness, division and the memory of defeat fuelled South African politics for almost a century thereafter.