José Eduardo dos Santos, a onetime Soviet-trained fighter against Portuguese colonial rule who in nearly four decades as Angola’s president became one of Africa’s longest-serving rulers — and was also accused of corruption on a grand scale — died on Friday in Barcelona, Spain, where he had been living in self-imposed exile. He was 79.
His death was announced on social media by the government of Angola, which said he died after a prolonged illness.
Under Mr. dos Santos’s rule, Angola fought and eventually won an enduring civil war against rebels backed by South Africa and the United States and supported insurgents challenging white minority rule in Namibia and South Africa. But he was widely accused of corruption and nepotism, and the economic boom he presided over benefited mainly his family and a coterie of advisers.
His daughter, Isabel dos Santos, ran the country’s state oil company and became Africa’s wealthiest woman, with a fortune once estimated by Forbes magazine at $3.5 billion. His son, José Filomeno de Sousa dos Santos, ran the country’s $5 billion sovereign wealth fund.
Inscrutable and wily in his politics, Mr. dos Santos was seen as a muscular player in regional diplomacy, steering events in the neighboring Democratic Republic of Congo and in Namibia to the south to secure his position at home.
His country also became a rear base for insurgents from the African National Congress fighting against apartheid rule in South Africa, and from the South West Africa People’s Organization, or SWAPO, fighting to end South African control of Namibia.
Like his predecessor, Agostinho Neto, independent Angola’s first president, Mr. dos Santos sought and received military assistance from Cuba at a time when rival superpowers had turned Africa into a Cold War checkerboard of proxy wars and ideological contests. Thousands of Cuban troops were stationed on Angolan soil to buttress his party, the Popular Movement for the Liberation of Angola, or MPLA.
His diplomacy was central to an accord in 1989 among South Africa, Cuba and Angola that allowed Namibia to declare its independence under a SWAPO government in 1990 after the withdrawal of Cuban forces from Angola.
Mr. dos Santos ruled his country for 38 years, from Mr. Neto’s death in 1979 — four years after Angola won independence from Portugal — until 2017, when he stepped down voluntarily as president, though not as leader of the dominant political party, the Popular Movement for the Liberation of Angola — a position he relinquished a year later.
His decades in power placed him in the uppermost reaches of a league of longtime African rulers, including Robert Mugabe of Zimbabwe and President Teodoro Obiang Nguema Mbasogo of Equatorial Guinea.
When he left the presidency, he was replaced by a chosen successor, João Lourenço, the country’s defense minister.
By that time, Mr. dos Santos had spent several years maneuvering family members into positions of staggering economic clout, and Angola, rich in diamonds and oil, had become infamous for its startling inequality. In its days as a liberation movement, the MPLA professed a belief in Marxism-Leninism, but it later switched its ideology to social democracy.
Expensive imported sports cars plied the streets of Luanda, the capital, and wealthy Angolans vacationed in luxurious Portuguese resorts, while many Angolans subsisted on pittances, denied health care and hope.
Despite the MPLA’S avowed ideological commitment to equality, some 70 percent of the population lived on less than $2 per day.
It was only a matter of months before Mr. Lourenço sought to distance himself from his predecessor, dismissing Ms. dos Santos, his daughter, from her position as head of Sonangol, the state oil company, along with its entire board of directors.
As revealed in a massive data leak in 2020, Ms. dos Santos was accused of plundering institutions including Sonangol, the state petroleum company, to create a business empire with stakes in diamond exports, the dominant cellphone company, banks and the country’s biggest cement maker.
In 2020, she was charged with embezzlement, money laundering and other financial crimes. She denied the charges, saying she was the victim of a witch hunt. She has been living mostly in Dubai, seeking to avoid arrest. Mr. dos Santos’s son was found guilty of financial transgressions and sentenced to five years in prison. He remained free on appeal.
José Eduardo dos Santos was born in Luanda on Aug. 28, 1942, the son of Avelino Eduardo dos Santos and Jacinta José Paulino. While still at school, he joined the MPLA, but he went into exile in Congo-Brazzaville in 1961 and later moved to Azerbaijan, which was then part of the Soviet Union. (Moscow was the MPLA’s principal backer.) He studied petroleum engineering and radar communications at the Azerbaijan Oil and Chemistry Institute in Baku.
He fathered children with several partners, including Tatiana Kukanova, the Russian-born mother of Isabel dos Santos; Filomena Sousa; and Maria Luisa Abrantes Perdigão. In 1991 he married a flight attendant, Ana Paula de Lemos.
Complete information on survivors was not immediately available.
In 1970 he returned to Angola and joined the underground MPLA forces fighting Portuguese rule as a radio operator in the oil-rich enclave of Cabinda. After a military coup d’état in Lisbon in 1974, Portugal’s colonial empire began to crumble. Angola secured its independence on Nov. 11, 1975.
Three rival liberation movements were still at war with one another, supported by rival backers and operating from different geographic power bases. The main contest was between the MPLA and Jonas Savimbi’s Western-backed National Union for the Total Independence of Angola, or UNITA. The MPLA called on Cuba to send troops when South African forces, encouraged by the C.I.A., pushed toward the gates of Luanda in support of UNITA.
The fight dragged on for years through successive iterations and efforts to reach a peace settlement. It finally petered out when Mr. Savimbi, the UNITA leader, died in 2002.
Over time, Mr. dos Santos, reflecting developments in Moscow and elsewhere, abandoned Marxist dogma in favor of a freewheeling capitalism that propelled an economic boom, which drew in foreign investors and made Angola Africa’s second-largest oil producer after Nigeria.
By the time of his death, investigators were still seeking to unravel his and his family’s dealings. But political analysts also questioned whether his successors were maneuvering for their own access to the country’s wealth.
Mr. Lourenço’s government seemed intent on clawing back as much of the missing billions as possible. As the influential British newsletter Africa Confidential put it, the tussle “is set to be a gargantuan legal battle stretching over many years.”
Gilberto Neto contributed reporting from Luanda, Angola.