23 April 1977
Zimbabwe African National Union (ZANU) leader, Robert Mugabe announced that Rhodesia's political organisations, ZANU and ZAPU (the Zimbabwe African People's Union), are to be merged under one command after the political affiliation of the two groups in the Patriotic Front. The merged Patriotic Front helped Mugabe defeat the colonial government of Ian Smith in 1980. Since then Mugabe has been in power for nearly 25 years.
References

Preston, M, Ending Civil War: Rhodesia and Lebanon in Perspective, from GoogleBooks, [online], Available at books.google.co.za [Accessed: 23 April 2014]|Cooper, G., Study Guide, from BREAKFAST WITH MUGABE, [online], Available at www.breakfastwithmugabe.com [Accessed: 23 April 20114]