The Orange Free State was an independent Boer sovereign republic in southern Africa during the second half of the 19th century, and later a British colony and a province of the Union of South Africa. It is the historical precursor to the present-day Free State province. Extending between the Orange and Vaal rivers, its borders were determined by the United Kingdom of Great Britain and Ireland in 1848 when the region was proclaimed as the Orange River Sovereignty, with a seat of a British Resident in Bloemfontein.
In the northern part of the territory a Voortrekker Republic was established at Winburg in 1837. This state merged with the Republic of Potchefstroom which later formed part of the South African Republic (Transvaal).
Following the granting of sovereignty to the Transvaal Republic, the British recognized the independence of the Orange River Sovereignty on 17 February 1854 and the country officially became independent as the Orange Free State on 23 February 1854, with the signing of the Orange River Convention. The new republic incorporated both the Orange River Sovereignty and the traditions of the Winburg-Potchefstroom Republic.
Although the Orange Free State developed into a politically and economically successful republic, it experienced chronic conflict with the British (see Boer Wars) until it was finally annexed as the Orange River Colony in 1900. It ceased to exist as an independent Boer republic on 31 May 1902 with the signing of the Treaty of Vereeniging at the conclusion of the Second Anglo-Boer War. It joined the Union of South Africa in 1910 (which became the Republic of South Africa in 1961) as a province under its former name, along with the Cape Province, Natal, and the Transvaal.
The republic's name derives partly from the Orange River, which in turn was named in honour of the Dutch ruling royal family, the House of Orange, by the Dutch settlers under Robert Jacob Gordon. The official language in the Orange Free State was Dutch.