head to Brazil and other territories than to Africa. To induce Europeans to move to its African holdings, the Portuguese government resorted to releasing degradados—convicted criminals—from prison in exchange for accepting what amounted to exile in Africa. Angola, in particular, gained a reputation as a Portuguese penal colony. Also, since the European population remained almost entirely male, the Portuguese birth rate was negligible, although plenty of "Afro-Lusitanians" were born to African mothers. As a result, the European population of Portugal's African settlements was never very large, and community leaders were just as likely to owe their loyalty to local African governments as they did to the distant Portuguese government. A second cause of weakness in Portuguese Africa was the effects of three centuries of Atlantic slave trade which had roots in the older African slave trade. Once the Atlantic triangular trade got underway, many Portuguese (including many Brazilian traders) in Africa found little incentive to engage in any other kind of profitable economic activity. The economies of Guinea, Angola and Mozambique became almost entirely devoted to the export of slaves to the New World (plus gold and ivory where they were available) while on the islands, slaves were used to grow sugar for export. Colonial authorities did nothing to stop the slave trade, which had sympathisers even among the several native African tribes, and many became wealthy by supporting it, while the traders themselves generated huge profits with which they secured allies in Africa and Portugal. Although anti-slavery efforts became organised in Europe in the 18th century, the slave trade only came to an end in the early 19th century, thanks in large part to English efforts to block shipping to the French during the Napoleonic Wars. Portugal was one of the first countries in the world to outlaw slavery, and did it so in mainland Portugal during the 18th century. The Portuguese government ended colonial slavery in stages with a final decree in 1858 that outlawed slavery in the overseas empire. The gradual pace of abolition was due to the strength of pro-slavery forces in Portuguese politics, Brazil and in Africa, they interfered with colonial administrators who challenged long-established and powerful commercial interests. The Napoleonic Wars added a new force to the Portuguese political scene—republicanism—introduced as an alternative to the monarchy by French troops in 1807. The French invasion induced the Portuguese royal family to make the controversial decision