Portugal founded Luanda in 1575 and Benguela farther south, and for two centuries Angola functioned, in the words of historians Oliver and Atmore, as "a gigantic slave-trading enterprise." Between 1580 and the 1820s, well over a million people were exported from the territory, most to Brazil. A mestico elite emerged in Luanda by the early 17th century, growing wealthy by facilitating the purchase and shipment of captives taken in wars and raids across the interior. The link between Angola and Brazil was so deep that Angola was sometimes described as a colony of Brazil rather than of Portugal. Brazilian ships dominated the ports of Luanda and Benguela, and Jesuit missionaries from Brazil shaped education and religion. Portuguese soldiers, traders, and degredados -- criminals shipped overseas to ease prison overcrowding -- manned the outposts. Service in Angola was deeply unpopular: pay was the same as in Portugal, but the cost of living was double, the death rate from disease was high, and the African population did not welcome the newcomers.

For most of its colonial history, Portugal controlled little beyond the coast. The interior kingdoms -- Kongo, Ndongo, Lunda, Mbunda -- remained independent or semi-autonomous. Portugal defeated the Kingdom of Kongo at the Battle of Mbwila in 1665 but suffered a disastrous loss trying to invade Kongo at the Battle of Kitombo in 1670. It was not until the late 19th century's Scramble for Africa, when rival European powers threatened to claim the interior, that Portugal pushed inland seriously. Treaties with the Congo Free State, Germany, France, and Britain between 1885 and 1905 fixed the borders. Then came the settlers. In 1900, Angola had 9,000 Portuguese residents. By 1974, it had 335,000 -- giving it the second-largest white population in sub-Saharan Africa after South Africa. The Estado Novo regime encouraged mass migration after 1951, when Angola was upgraded from colony to overseas province. The newcomers dominated business, the professions, and the coffee plantations, while the indigenous African majority found itself locked out of educational opportunities and menial occupations alike.

Armed resistance began on March 15, 1961, when Holden Roberto led 4,000 to 5,000 militants into northern Angola, overrunning farms and government outposts. At least 1,000 whites and an unknown number of black Angolans were killed. "This time the slaves did not cower," Roberto said. Portugal responded with thousands of troops from Europe. Three guerrilla movements emerged, divided by ethnicity and ideology. The MPLA, led by mestico intellectuals, drew support from the Mbundu people and Luanda's urban population. Roberto's FNLA was rooted among the Bakongo. Jonas Savimbi broke away to found UNITA in 1966, drawing on the Ovimbundu, Angola's largest ethnic group. The movements fought Portugal -- and frequently each other. By 1972, after a major counterinsurgency campaign on the eastern front, the Portuguese had largely contained the guerrillas militarily. But they could not win the political war. International sanctions, arms embargoes, and growing opposition at home made the colonial conflict unsustainable.

On April 25, 1974, Portuguese military officers overthrew the Estado Novo dictatorship in Lisbon in what became known as the Carnation Revolution. The new government declared a truce with all African guerrilla movements. Within months, the colonial edifice that had taken five centuries to build was dismantled. The Alvor Agreement set November 11, 1975 as independence day. What followed was a mass exodus. Hundreds of thousands of Portuguese settlers -- overwhelmingly white, but some mestico and black -- fled Angola, most with little more than what they could carry. They became the retornados, a generation of refugees who arrived in a Portugal that was itself in upheaval. The newly independent People's Republic of Angola, renamed the Republic of Angola in 1992, inherited a country whose infrastructure, economy, and professional class had largely departed. Brazil was the first country to recognize the new nation -- a fitting bookend to a relationship that had begun with slave ships crossing the same ocean in the opposite direction.