For four centuries Portugal's grip was thinner than the maps suggested. Coastal posts were built, abandoned, and rebuilt; governors came to make their fortunes and leave. The settlers who stayed were traders who married local women and kept careful relations with African chiefs, while the Mwenemutapa and other inland kingdoms went on largely undisturbed. Portugal cared more about the spice trade with India and the colonization of Brazil. To control the interior, the crown handed out prazos - vast land grants that, through intermarriage, became African-Portuguese estates defended by armies of enslaved soldiers called Chikunda. Slavery was woven through the whole arrangement. People were bought and sold by African chiefs, Arab traders, and the Portuguese alike, and many of the enslaved were captives sold by chiefs who raided rival communities.

When the Scramble for Africa forced Europe to draw hard borders, Portugal had to actually occupy what it claimed. It waged war against African polities into the early twentieth century, and it built a state designed to extract labor. Even after slavery was formally abolished, the chartered companies that ran much of the territory enacted forced-labor policies, supplying cheap and often coerced African workers to mines and plantations across southern Africa. The 1929 Statute of Indigenous Populations made the inequality law: it split society into citizens, who held Portuguese rights, and indígenas, the African majority, who were subject to customary authority, pass laws, and unpaid forced labor. A small middle group, the assimilados, could escape forced labor only by proving they had become, in the colonizer's eyes, sufficiently European. Behind the talk of a civilizing mission was a system built to keep most people poor and working.

By the mid-twentieth century the contradictions had a price tag. The economy boomed in the 1950s and 1960s, drawing tens of thousands of Portuguese settlers and foreign capital - British sugar concessions, Belgian-financed coal at Moatize, the great Cahora Bassa dam begun in 1969. By independence, Mozambique had one of the more developed industrial bases in sub-Saharan Africa. But the wealth was deeply unequal. In 1970, after generations of segregated schooling, only about 7.7 percent of the population could read. The statistics were blunt: roughly a quarter-million Europeans, around 3 percent of the people, held the skilled jobs, the good schools, and the capital, while millions of Africans were locked out of the prosperity their labor produced. From this gap the independence movement grew.

In September 1964, the Front for the Liberation of Mozambique - FRELIMO, led by Eduardo Mondlane and headquartered in Tanzania - opened a guerrilla campaign against Portuguese rule. It became one front of the Portuguese Colonial War, fought simultaneously in Angola and Guinea, and it dragged on for a decade. The war consumed a punishing share of Portugal's budget and patience, and it was the soldiers themselves who ended it: on 25 April 1974, officers in Lisbon overthrew the Estado Novo regime in the nearly bloodless Carnation Revolution. The new government offered independence to the colonies. Mozambique became free on 25 June 1975. Within a year almost the entire Portuguese population had gone, leaving as refugees the homeland called retornados - some expelled, many simply afraid - and a new nation inherited both a rare industrial base and the deep scars of what had built it.