In the aftermath of the conventional military victory won by British forces, the Boers launched a guerrilla war. The British responded by taking action against the civilian population. At one point, the British acknowledged that they were holding over 100,000 people in concentration camps.
The second phase of the Boer War, beginning roughly in mid-1900 and continuing until its conclusion in 1902, was markedly different in its character. With their capitals captured and their formal armies dispersed, the Boers shifted to guerrilla tactics to continue the fight against the British.
Under the leadership of generals like Louis Botha, Jan Christiaan Smuts, and Koos de la Rey, the Boers operated in small, mobile units, launching hit-and-run attacks on British columns, derailing trains, and ambushing patrols. This strategy aimed to stretch the British thin, forcing them to guard every rail line, bridge, and supply depot, making them vulnerable to sudden assaults.
The British, under Lord Kitchener, responded with a "scorched earth" policy. They burned Boer farms, destroyed their crops, and confiscated livestock. This was done to deny the Boer guerrillas supplies and support from the local population. The most controversial aspect of this policy was the establishment of concentration camps where Boer civilians, mainly women and children, were interned. The conditions in these camps were deplorable, resulting in thousands of deaths.
Despite these tactics, the guerrilla phase of the war proved challenging for the British. The vast South African landscape, combined with the Boers' intimate knowledge of the terrain, made it a daunting task for the British to establish control.
It was only in 1902, after protracted negotiations and continued guerrilla actions, that the war finally came to an end with the signing of the Treaty of Vereeniging. This guerrilla phase of the war is a testament to the determination of the Boers, who, despite being outnumbered and outgunned, managed to prolong the conflict and extract significant concessions from a global superpower.