Revolution military coup of April 1974 in mainland Portugal. The withdrawal resulted in the expulsion of hundreds of thousands of Portuguese citizens plus military personnel of European, African, and mixed ethnicity from the former Portuguese territories and newly independent African nations. This migration is regarded as one of the largest peaceful, if forced, migrations in the world's history although most of the migrants fled the former Portuguese territories as destitute refugees. The former colonies faced severe problems after independence. Devastating civil wars followed in Angola and Mozambique, which lasted several decades, claimed millions of lives, and resulted in large numbers of displaced refugees. Angola and Mozambique established state-planned economies after independence, and struggled with inefficient judicial systems and bureaucracies, corruption, poverty and unemployment. A level of social order and economic development comparable to what had existed under Portuguese rule, including during the period of the Colonial War, became the goal of the independent territories. The former Portuguese territories in Africa became sovereign states, with Agostinho Neto in Angola, Samora Machel in Mozambique, Luís Cabral in Guinea-Bissau, Manuel Pinto da Costa in São Tomé and Príncipe, and Aristides Pereira in Cape Verde as the heads of state. Political context 15th century When the Portuguese began trading on the west coast of Africa in the 15th century, they concentrated their energies on Guinea and Angola. Hoping at first for gold, they soon found that slaves were the most valuable commodity available in the region for export. The Islamic Empire was already well-established in the African slave trade, for centuries linking it to the Arab slave trade. However, the Portuguese who had conquered the Islamic port of Ceuta in 1415 and several other towns in current-day Morocco in a Crusade against Islamic neighbors, managed to successfully establish themselves in the area. The Portuguese, though, never established much more than a foothold in either place. In Guinea, rival European powers had established control over the trade routes in the region, while local African rulers confined the Portuguese to the coast. These rulers then sent enslaved Africans to the Portuguese ports, or to forts in Africa from where they were exported. Thousands of kilometers down the coast, in Angola, the Portuguese found consolidating their early advantage in establishing hegemony over the region even harder, due to the encroachment of Dutch traders. Nevertheless, the fortified Portuguese towns of Luanda (established in 1587 with 400 Portuguese settlers)