Q&A: Angola's war

Rebel leader Jonas Savimbi, who led Unita for more than 30 years, has been killed in Angola. His death is likely to be a key moment in the country's history.

Who was Jonas Savimbi?

Jonas Savimbi founded Unita - the National Union for the Total Independence of Angola - in the late 1960s as a rival movement to the Popular Movement for the Liberation of Angola (MPLA), which later became the government.

Savimbi's first chance of power came with the end of Portuguese colonialism in 1975.

But promised a share in a transitional government with the National Front for the Liberation of Angola (FNLA) and the MPLA, Unita lost out and took up arms against those two, more established, liberation movements.

What happened after independence?

Peace agreements reached in 1974, 1989 and 1991 all collapsed.

Elections were then held during a ceasefire in 1992, but Unita did not accept the results and fighting resumed.

Another attempt to find peace in 1994 with the Lusaka accord finally broke down in 1998, and the country returned to war.

The conflict in Angola is estimated to have killed more than 500,000 people, and displaced hundreds of thousands of others.

Why has the war lasted so long?

Unita's survival owed much to its alliance with apartheid South Africa, which remained at war with Angola for much of the next 15 years, and to the United States, while the Soviet Union and Cuba supported the then-Marxist MPLA.

When the support of those allies faltered with the end of the cold war, the war became a battle of oil against diamonds.

Unita funded its war almost entirely with the diamonds found on the territories it held, while the Luanda-based government relied largely on oil.

Class, race and ethnic divisions have also had their part to play in keeping the conflict alive.

For example, the Ovimbundu people, Unita supporters found mostly in the central highlands, are pitted against the coastal and Kimbundu peoples.

Does Savimbi's death mean the end of the war?

The reports of Jonas Savimbi's death come at a time when the United Nations is talking of progress towards a peaceful settlement in Angola and organisations in Angolan society were urging a bilateral ceasefire.

Observers say Mr Savimbi's death would remove a major obstacle to the establishment of peace and the achievement of the dream of co-ordinated economic development across the region.

However, Unita guerrillas remain scattered over a wide area of the country so their leader's death will not end the war automatically, says the BBC's Angola correspondent Justin Pearce.

And those who are working for a peaceful settlement will have lost the chance to negotiate with the one man who could have brought the conflict to an immediate halt.