30 January 1979
Chief among the factors that led to the adoption of a new constitution in Rhodesia on the 30 January 1979 (now Zimbabwe) was that Ian Smith, the Rhodesian Prime Minister, at the time, unilaterally declared independence from Britain in an effort to hold on to white minority rule. However this move, regardless of the support Rhodesia received from South Africa demonstrated the non feasibility of minority rule as it led to an intensification of guerrilla activities by the liberation movements in Rhodesia that included Zanu (Zimbabwe African National Union), Zapu (Zimbabwe African Peoples Union) and others against the white minority government These activities, known as the second Chimurenga (uprising) brought enormous pressure from within Africa as well as abroad to bear upon Rhodesia. While most Western countries ignored the sanctions against Rhodesia, the extent of the internal uprising was so great that Smith had no choice but to adopt a new constitution granting all Rhodesians the right to vote, eliminating discriminatory laws and agreeing to a general election whereby the government would reflect the true composition of the Rhodesian populace.
References

Business Day Live,"Zimbabwe adopts new constitution",From: Business Day Live,[Online], Available at:www.bdlive.co.za,[Accessed: 20 December 2013]|

Project Advisor, (2005) THE RHODESIAN INSURGENCY: A FAILURE OF REGIONAL POLITICS, USAWC STRATEGY RESEARCH PROJECT