Prime Minister of Rhodesia held the post until the end of Federation on 31 December 1963. When Northern Rhodesia gained independence as Zambia on 24 October 1964, Southern Rhodesia began to refer to itself simply as "Rhodesia". Prime Minister Ian Smith's government issued a Unilateral Declaration of Independence from Britain in 1965, and he remained Prime Minister when the country was declared a republic in 1970. Under the Internal Settlement in 1979, after a long period of conflict, the country became known as Zimbabwe-Rhodesia, with Abel Muzorewa as its first black Prime Minister. None of these acts were recognised internationally, and under the Lancaster
Northern Rhodesia these copper deposits could not be exploited commercially until the Southern Rhodesian railway had extended across the Zambezi and continued northward, to reach the Belgian Congo border, which it did in 1909. By that time, mining had started in Katanga, where rich copper oxide ores occurred near the surface. In Northern Rhodesia, the surface ores were of poorer quality, and copper was only worked intermittently at Bwana Mkubwa, until in 1924 rich copper sulphide ores were discovered about 100 feet below the surface. Prior to 1924, there had not been significant exploitation of Northern Rhodesia's mineral resources: there was some