The Angolan struggle for independence from Portugal produced a spectrum of rival nationalist groups representing different sectors of society. With independence granted in 1975, the Movimento Popular da Libertação de Angola (Popular Movement for the Liberation of Angola, MPLA) rapidly quelled the opposition of the Frente Nacional de Libertacão de Angola (the National Liberation Front of Angola, FNLA) and became the de facto government. However, despite considerable international recognition, the MPLA government faced continuing challenges to its authority. Foremost among these was the sustained war against the government by the União Nacional para a Independência Total de Angola (National Union for the Total Independence of Angola, UNITA) facilitated by Zairean, South African and Western military assistance, as well as diamond revenue. Its leader, Jonas Savimbi, refused to acknowledge the legitimacy of the MPLA, even with his electoral defeat to MPLA leader Eduardo dos Santos in 1992. Initial hope that the devastating war would end with the withdrawal of Cold War funding proved premature, with fighting intensifying from 1992 to 1994. UNITA and the government of Angola signed a ceasefire agreement on 4 April 2002.