Boer republic of the Transvaal, defeated by Britain in the Second Boer War.
The South African Republic (ZAR) ceased to exist on 31 May 1902 when the Treaty of Vereeniging ended the Second Boer War; it became the British Transvaal Colony and joined the Union of South Africa in 1910.
Definitive narrative of the war that ended the Transvaal republic's independence.
The European partition that hemmed in and ultimately overran the Boer republics (broad context).