The Second Boer War (Dutch: Tweede Boerenoorlog, Afrikaans: Tweede Vryheidsoorlog or Tweede Boereoorlog) was fought from 11 October 1899 until 31 May 1902 between the British Empire and the Afrikaans-speaking Dutch settlers of two independent Boer republics, the South African Republic (Transvaal Republic) and the Orange Free State. It ended with a British victory and the annexation of both republics by the British Empire; both would eventually be incorporated into the Union of South Africa, a dominion of the British Empire, in 1910. The conflict is commonly referred to as The Boer War but is also known as the South African War outside South Africa, the Anglo-Boer War among most South Africans, and in Afrikaans as the Anglo-Boereoorlog or Tweede Vryheidsoorlog ("Second War of Liberation" or lit. "Second Freedom War") or the Engelse oorlog (English War).

The Second Boer War and the earlier, much less well known, First Boer War (December 1880 to March 1881) are collectively known as the Boer Wars.