 Mandated by the results of the 1953 referendum , Federation began later that year with Southern Rhodesia , the most developed of the three territories , at its head . Salisbury doubled as Federal capital . The Federation was granted several privileges by Britain during its earlier years ; for example , a 1957 British Act of Parliament empowered it to appoint its own " diplomatic agents , or consular or trade representatives , in countries which are willing to receive them " so long as it informed Britain when it was doing so . The most prominent of these appointments was made in 1961 , when the Union of South Africa split from the Commonwealth of Nations and became a republic . An accredited representative of Salisbury was set up in Pretoria soon after , independent of Britain 's embassy there . An independent office representing the Federation was also set up in Lourenço Marques , the capital of Portuguese Mozambique , while further afield , Federal officials were set up within the British embassies in West Germany , Japan and the United States . 
