A leftist military-led coup d'état, started on April 25, 1974, in Lisbon, overthrew the Marcelo Caetano government in Portugal, and promised to hand over power to an independent Angolan government. Mobutu Sese Seko, the President of Zaire, met with António de Spínola, the transitional President of Portugal, on September 15, 1974 on Sal island in Cape Verde, crafting a plan to empower Holden Roberto of the National Liberation Front of Angola, Jonas Savimbi of UNITA, and Daniel Chipenda of the MPLA's eastern faction at the expense of MPLA leader Agostinho Neto while retaining the façade of national unity. Mobutu and Spínola wanted to present Chipenda as the MPLA head, Mobutu particularly preferring Chipenda over Neto because Chipenda supported autonomy for Cabinda. The Angolan exclave has immense petroleum reserves estimated at around 300 million tons (~300×109 kg) which Zaire, and thus the Mobutu government, depended on for economic survival.After independence thousands of white Portuguese left, most of them to Portugal and many travelling overland to South Africa. There was an immediate crisis because the indigenous African population lacked the skills and knowledge needed to run the country and maintain its well-developed infrastructure.
The Angolan government created Sonangol, a state-run oil company, in 1976. Two years later Sonangol received the rights to oil exploration and production in all of Angola. After independence from Portugal in 1975, Angola was ravaged by a horrific civil war between 1975 and 2002.