The Boer Republics of the ZAR and the Orange Free State were united with the Cape Colony and Natal Colony in 1910 to become the Union of South Africa. Pretoria then became the administrative capital of the whole of South Africa, with Cape Town the legislative capital. Between 1860 and 1994, the city was also the capital of the province of Transvaal, superseding Potchefstroom in that role. The new Union required a governmental building which could signify unity and host the new government.