However, British fortunes changed when their commanding officer, General Redvers Buller, was replaced by Lord Roberts and Lord Kitchener, who relieved the besieged cities and invaded the Boer republics in early 1900 at the head of a 180,000-strong expeditionary force. The Boers, aware they were unable to resist such a large force, refrained from fighting pitched battles, allowing the British to occupy both republics and their capitals, Pretoria and Bloemfontein. Boer politicians, including President of the South African Republic Paul Kruger, either fled or went into hiding; the British Empire officially annexed the two republics in 1900. In Britain, the Conservative ministry led by Lord Salisbury attempted to capitalise on British military successes by calling an early general election, dubbed by contemporary observers as a "khaki election". However, Boer fighters took to the hills and launched a guerrilla campaign, becoming known as bittereinders. Led by generals such as Louis Botha, Jan Smuts, Christiaan de Wet, and Koos de la Rey, Boer guerrillas used hit-and-run attacks and ambushes against the British for two years.
However British fortunes changed when their commanding officer General Redvers Buller was replaced by Lord Roberts and Lord Kitchener who relieved the besieged cities and invaded the Boer republics in early 1900 at the head of a 180000-strong expeditionary force The Boers aware they were unable to resist such a large force refrained from fighting pitched battles allowing the British to occupy both republics and their capitals Pretoria and Bloemfontein Boer politicians including President of the South African Republic Paul Kruger either fled or went into hiding; the British Empire officially annexed the two republics in 1900 In Britain the Conservative ministry led by Lord Salisbury attempted to capitalise on British military successes by calling an early general election dubbed by contemporary observers as a "khaki election" However Boer fighters took to the hills and launched a guerrilla campaign becoming known as bittereinders Led by generals such as Louis Botha Jan Smuts Christiaan de Wet and Koos de la Rey Boer guerrillas used hit-and-run attacks and ambushes against the British for two years