2 September 1980
Zimbabwe announced it had severed diplomatic relations with South Africa, but would maintain a trade mission in Johannesburg. The ending of diplomatic relations between the two southern African countries happened just five months after Rhodesia gained independence after ninety years as a British colony, renaming itself Zimbabwe. Robert Mugabe, head of the Zimbabwe African National Union (ZANU), became the first Prime Minister.
References

 South African History Online, ‘Rhodesia gains independence as Zimbabwe’, [online], available at www.sahistory.org.za (Accessed: 20 August 2013)|

O’Malley, P. ‘1980’, from Nelson Mandela Centre of Memory, [online], available at www.sahistory.org.za|

African History, ‘This week in African history: Week starting Monday 14 April’, [online], available at https://africanhistory.about.com (Accessed: 20 August 2013)