Following the British annexation of Transvaal in October 1900, the conflict in South Africa entered a second phase: guerrilla war. Although the British controlled the towns and railways, the Boer commandos were still able to operate on the veldt where they were supported by their families. Having grown up on the veldt they knew the terrain and used its features to their advantage. Kopjes (hills) and dongas (riverbeds) suited marksmen as they provided natural cover in an otherwise open landscape.
To counter this advantage, General Lord Kitchener instigated a new strategy of hunting down the remaining Boers with the use of mobile columns. Boer families that were deemed sympathetic to the commandos were removed from their farms and imprisoned in concentration camps. The livestock of these Boer farmers were either taken into British possession or slaughtered.
Towards the end of 1901 Kitchener and Lord Alfred Milner devised a new strategy which they hoped would successfully end of the war. Rather than remove the women and children to concentration camps, the British decided to simply leave them in the ruins of their former farms so that they would become an unnecessary burden to the Boer guerrillas. To secure the countryside, lines of blockhouses were constructed and linked by fences of barbed wire. Nearly 8000 blockhouses had been built by the end of the war, altogether covering 6000 km. The mounted columns would drive any Boers that they encountered towards the blockhouses, which were manned by an armed garrison. Cut off from any possible escape, the Boers would be forced to surrender.
The last major engagement involving New Zealand troops took place as a result of these blockhouse drives. Pursued by the imperial forces, the leaders of the Orange Free State, President Steyn and General Christiaan De Wet, decided to break through the lines being held by the New Zealand Seventh Contingent at Langverwacht Hill. On the night of 23 February 1902 the Boers overwhelmed the New Zealand posts and opened up a gap in the line large enough for them to escape through. Despite fighting gallantly, 24 of the 80 New Zealanders were killed and another 40 wounded.
The final New Zealander to die in action was Lieutenant Robert McKeich of the Ninth Contingent on 4 June 1902. Just four days after the peace treaty had been signed he and Lieutenant Henry Rayne rode out into the countryside to hunt. There they were confronted by three Boers who did not believe that the war was officially over. After resisting the Boer demands for their clothes and weapons, McKeich was shot dead. Rayne managed to escape after killing one of the Boers and wounding the other two, one of whom later died of his wounds.