A main reason for the demise of the Northeast  was slavery, or rather its end. Since Brazil ’s earliest days as a colony, an estimated 10 million slaves had been shipped across the Atlantic from Africa—roughly 10 times the number transported to the United States. Despite the cruel punishments they faced, many slaves revolted. Countless others escaped. Throughout Brazil, but particularly in the Northeast, the fugitives established isolated communities known as quilombos.
Although they lived a subsistence existence, many were able to preserve the religious and cultural traditions of their African ancestors, some of which survive to this day. The most biggest and most famous quilombo of Palmares, located in northern Alagoas, functioned as a veritable republic. Led by the fierce warrior Zumbi, the quilombo was able to defend itself from white settlers and government troops for years. Although Zumbi was finally betrayed and killed, he became a national symbol of black resistance.
However, there was no way Brazilian plantation owners were going to give up their lifestyle and wealth by voluntarily liberating slaves, as dictated to them by their English trading partners, who abolished slavery in 1807. Although they paid lip service to the British by pretending to embark upon reforms, in reality their efforts were para inglês ver (“for the English to see”)—an expression that is still used today to express the act of pretending to do something (but not really doing it).
The English weren’t fooled. During the 1830s and ’40s, they sent navy vessels to the Brazilian coast to capture slave ships and confiscate their human cargo. As a result, Brazil abolished the slave trade in 1854, but slavery was still legal in Brazil. As a growing abolitionist movement spread across more enlightened regions of the country, Dom Pedro II reluctantly signed laws freeing the children of female slaves (1871) and (the very few) slaves over the age of 65 (1885).
Finally, on May 13, 1888, his daughter, Princesa Isabel, signed the Lei Áurea, giving Brazil the dubious distinction of being the last of the New World nations to ban slavery.
The end of slavery had several major repercussions. It brought about the demise of the northeastern sugar and cotton plantation economies and caused the region (and its land-owning elite) to enter a long period of decadence that would take a century to recuperate from. It also created a vast population of free but poor and uneducated black Brazilians, who had to fend for themselves and find work (a phenomenon that often sadly led to a life of “paid” slavery).
Politically, abolition was the final straw that broke the Brazilian empire. For some time, fueled by Europe’s republican tendencies, Brazil ’s growing urban intellectual classes had been clamoring for the end of the monarchy. Increasingly, Pedro II’s staunchest defenders had been the conservative land-owning elite. But when he had the gall to end slavery, they too turned their backs on him. The final nail in the emperor’s coffin was the ill-fated Paraguay War (1865–1870), in which Brazil, Argentina , and Uruguay ganged up on their puny, but fierce, neighbor Paraguay.
Although they practically eliminated the male population of Paraguay, the powerful allies didn’t emerge unscathed from battle. Brazil lost 100,000 men and racked up serious debts, and Pedro II lost the support of the military. In 1889, a group of army officers, led by Marechal (Marshall) Manuel Deodoro da Fonseca, staged a bloodless coup d’état. Dom Pedro returned to Europe, where he died two years later in Paris.