The war was caused by the propaganda of Lord Alfred Milner against the government of the Transvaal, in which he claimed that they refused to grant equal voting rights to the many thousands of (largely British) settlers who had flocked to the area to exploit the gold mines of the Rand, while the mine owners sought to replace the government of President Paul Kruger with one more compliant to their interests. History shows that Milner's claims were false, though, as the Transvaal government offered to dramatically shorten the time a British citizen had to live in the South African Republic before receiving voting rights. Milner's propaganda was made in an attempt to find a reason to declare war on the Boer Republics, in order to expand the British Empire across Africa. An attempted coup - the 'Jameson Raid' (Dec 29 1895-Jan 2 1896) - backed by the Prime Minister of the Cape colony, Cecil Rhodes, failed, which let the Boers know that war was to follow.
In September 1899 the British Colonial Secretary Joseph Chamberlain issued an ultimatum demanding equal rights for the British within the republics. They retorted with an ultimatum of their own; if the British did not withdraw troops from the border within 48 hours they would declare war.
Initially the war was fought in the traditional style of pitched battles. Due to their expertise with the terrain and the disorganization of the British the Boers were initially successful, launching offensives into the British colonies, and defeating British offensives during 'Black Week' in December 1899 which saw British defeats at the Battles of Stormberg, Magersfontein and Colenso. However the immense capacity of the British Empire was brought to bear, and the Boer Commandos were pushed back into their own states. The conflict then degenerated into a guerrilla war. The British found that they could only control the territory they physically occupied. But a mixture of new infantry tactics, fixed defenses and the disillusionment of the native Africans with the Boers combined to end in the surrender of the Boer forces in May 1902.
The British systematically destroyed Boer crops, and killed cattle in order to deny food to the Boer Army. Boer houses were also burned. They forced Boer civilians into internment camps which were known as concentration camps where over 27,000 died because of hunger and disease. Most of the victims were children and old people and this caused great bitterness among Boers who regarded the death-toll as a war crime.
The war officially ended with the signing of the Treaty of Vereeniging, which gave the Boers approximately $5,700,000 to reconstruct and established the Union of South Africa, which was absorbed into the British Empire. The total number of casualties during the war was around 75,000, of which 22,000 were British soldiers, 7,000 were Boer soldiers, 25,000 were Boer civilians (many of whom died in insanitary internment camps set up by the British) and possibly 20,000 black Africans. However the majority of the British casualties were as a result of disease and not through enemy fire.