Boer republic between the Orange and Vaal rivers, also annexed after the Second Boer War.
The Orange Free State was annexed by Britain as the Orange River Colony on 31 May 1902 via the Treaty of Vereeniging ending the Second Boer War; it became a province of the Union of South Africa in 1910.
The Anglo-Boer war that led to the Free State's annexation.
Broad South African history situating the Free State republic.