7 February 1980
Transkei announced it was re-establishing diplomatic relations with South Africa following Pretoria’s undertaking to negotiate over disputed land. The break of diplomatic relations between South Africa and Transkei became official when Kaizer Daliwonga Matanzima announced on 10 April 1978 that Transkei would break all diplomatic ties. This included a unilateral withdrawal from the non-aggression pact between the two governments, and the demand that all South African Defence Force (SADF) members seconded to the Transkei Army should leave. The dispute dates back to the late 1970s when Transkei demanded areas the apartheid government had designated as “white” to be part of the homeland.
References

O’Malley, P. ‘1980’, from Nelson Mandela Centre of Memory and Dialog, [online], available at www.nelsonmandela.org.za (Accessed: 08 January 2013)|

South African History Online, ‘Minister of Bantu Administration and Development, MC Botha announces that he will not stand for re-election’, [online]  ,available at www.sahistory.org.za (Accessed: 08 January 2013)