On 11 November 1965, he made his Unilateral Declaration of Independence. Rhodesia had cast itself adrift from Britain and the Commonwealth.
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The world community refused to recognise Rhodesia and the United Nations applied economic sanctions, but many international companies secretly broke them - and apartheid South Africa seemed especially keen to chip in.
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"I don't believe in black majority rule over Rhodesia," he defiantly proclaimed at the time, "not in a thousand years."
In the end he had to. But it was not British diplomacy which eventually wore him down but armed black opposition and, decisively, Pretoria's decision to withdraw support for his government.
Source:
http://news.bbc.co.uk/2/hi/africa/1136865.stmEdited to correct an error.