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What if the Atlantic Slave Trade had ended early?

By Steve Payne and Jeff Provine

This article was originally posted on Today in Alternate History (twitter) and the original article can be found there. Please check that blog for more like this.

Achille Devéria's painting of Queen Nzinga

The first Portuguese Sailors arrived in modern day Angola in 1483. They were there to establish alliances, trade and a path to Asia and one of the things they were most eager to trade was Slaves, having known for decades that the nations of the Sahel sold slaves across the Sahara to the North African polities. More active interest can be dated to Antam Gonçalve in 1441 who had raided modern Day Western Sahara for slaves, capturing around 10 Berbers who he later ransomed in return for Sub Saharan slaves. In response to this growing economic possibility, Pope Nicolas V issued two papal bulls in 1452 and 1455 granting Portugal the right to enslave sub-Saharan Africans. They granted the right to invade, plunder and "reduce their persons to perpetual slavery." This brutal treatment of "black Gentiles" was considered a natural deterrent and Christianizing influence to "barbarous" behaviour among pagans.

When the Portuguese first arrived in Angola, they made contact immediately with the subjects of the Kingdom of Kongo, the dominant central African kingdom. Over the next few years they would convert the King of Kongo to Catholicism and leave Portuguese architects, doctors and priests at his court. They would also take Kongolese nobles to Portugal to be educated and in many cases to become clergy. And, of course, they made an agreement to buy slaves.

Originally the slaves mostly weren’t going to the New World, some were going to Europe and a lot were staying in Africa where the Portuguese were trying to create plantations and trading routes across the Gulf of Guinea. It was only in the 16th Century that the New World slave system got kick-started and so the numbers of slaves the Portuguese were buying became unusual and dangerous as they attempted to build sugar plantations in Brazil where the slaves died in much greater numbers.

In the 1520s King Afonso of Kongo began to panic because suddenly slaves were being taken at a much larger rate and it was destabilising his country. Afonso's letters to the Kings of Portugal display a concern that the slave trade was getting out of his control, that it was not just captives of wars but free born Kongolese also being sold because ultimately the Portuguese goods were so much more valuable that laws were being broken so that they could be obtained. The treaty was that Kongo would sell slaves to Portugal but it was understood that it was slaves that were to be sold not free people as slaves. So Afonso urged the Portuguese kings to reign back their merchants, they didn’t and Afonso couldn’t control his own people either.

But he could buy back free people who had been sold. Throughout the 16th Century, agents of the Kongolese King visited São Tomé and Príncipe, a stop off point between Kongo and Brazil, and found nobles and elites who had been illegally sold and bought them back. In 1604, they went further and travelled to Brazil itself to buy back slaves who had been taken to the plantations, the result was probably the first ever New World slaves to be returned to their homes in Africa.

But the number of slaves kept increasing, Portugal extracted slaves at a rate of 10,000 per year by 1612. Then in 1619, the first enslaved Africans to arrive in the British colony of Virginia were Ndongans onboard the White Lion. They had been kidnapped by Portuguese colonial forces, who sent captured members on a forced march to the port of Luanda. Ordered onto the ship São João Bautista, which set sail for Veracruz in the colony of New Spain (Spain and Portugal had been united under one Monarch by this point), about 150 of the 350 captives aboard the ship died during the crossing. Then, as it approached its destination, the ship was attacked by two privateer ships, the White Lion and the Treasurer. Crews from the two ships kidnapped up to 60 of the Bautista's enslaved people and took them to British colonies to work. North European nations such as the British and the Dutch were firmly now aware of the slaves leaving the Kingdom of Kongo and had their interest piqued.

Meanwhile the leaders of the Kongo were still trying to use their contacts to reduce the slave trade and in 1623, the Kongolese Ambassador to the Vatican achieved a landmark victory. He secured an agreement with the Pope and King Philip IV of Spain and Portugal that no Kongolese Christians should be enslaved at all, only pagans, after all the original papal bills justifying the enslavement of Africans had been aimed at pagans not the Christian Kongolese. Philip even sent a ship load of Christian slaves back to the Kingdom of Kongo as a result.

Why did the Spanish agree to this? It was mostly a way to try and rebuild bridges with a potential enemy.

Earlier that year the Iberian Governor of Angola had been defeated in an unsuccessful invasion of the Kongo, something which had been hugely controversial as Jesuit priests in the region reported in horror that pagan African soldiers in the Spanish Army had been allowed to both enslave and indeed eat African Christian civilians in that failed invasion. After the Kongolese had crushed the invading army, there had been anti Portuguese riots and the Kongolese King, accused of being too friendly with the Europeans, had asked Philip and the Pope to denounce the Governor and prove themselves friends. The agreement on slaves was their reply and an effective apology for the invasion of the previous year. In 1624, a Dutch fleet arrived in Angola hoping to launch a joint attack on Luanda with the Kongolese after having received an offer of alliance from the King of Kongo in 1622.

The Kongolese however, placated by the agreement of 1623, didn’t show up, and the Dutch withdrew. Philip’s gamble had worked to preserve his colony from the threat of the Dutch and with that danger passed, no more Catholic slaves were returned and more and more were bought as Kongo fell into Civil War, racial hierarchies overtook religious ones in Europe and the stature of African Christians within the Catholic Church fell. The 1623 agreement became one of many Clerical attempts to restrain Christian brutality that ultimately had little long term effect along with the similar efforts in the Americas by the likes of Bartolomé de las Casas and Antonio Ruiz de Montoya.

Without any restraint placed on the trade, Angola became one of the great supplying sources right up until the mid-19th century. Portugal, the creators of the Atlantic slave Trade, were the largest traders in slaves of any country involved in it, with the British in second. An early end to the ability of the Portuguese to obtain slaves from that region changes the lives of millions of people for the better. Almost 5.7 million slaves left Angola between 1501 and 1866 and were sent across the Atlantic where they died in horrific numbers, in the cramped disease filled boats of the crossing, in the awful conditions they laboured under particularly in the Sugar plantations and at the hands of their masters, who used routine torture and murder to keep order. Over one third of captured Africans died within the first year, the median life expectancy of those who made in to the New World was only seven years, and the death rate was so high that the Portuguese slave populations were never self sustaining. This was not helped by the way slaves were often worked so hard they couldn't bear children, roughly half of female slaves in the sugar plantations were infertile and those that did give birth were often the results of rape by their white masters. As a result the plantations were reliant on new slaves so the trade was massive and African slaves were so sought after that large areas of Africa were destabilised as a result of slaving bands roaming far and wide to find victims.

If the agreement of the 1620s could be maintained and extended and the slave trade reduced, Africa would be much better off through the 17th and 18th centuries and be less likely to be so vulnerable to European imperialism in the 19th and 20th centuries. One central figure in such a change might well be Queen Nzinga of Ndongo and Matamba. Nzinga is a tricky figure to grasp as the written reports on her were mainly written by people from outside her country and as such she has been interpreted as both a patriotic anti-imperialist and a quisling collaborator with the Portuguese slavers.

Two factors primarily informed Nzinga's rule, first the Portuguese under their Spanish King had taken a much more active role in Central African politics and between 1612 and 1622, in alliance with the Imbangala people, had won a series of stunning victories, destroying several smaller states and capturing thousands of slaves, something that would lead to the ill fated attack on Kongo itself in 1623. This upended the previous status quo and established the Portuguese as a major factor in Mbundu Politics. Secondly, Nzinga herself was both a woman and the daughter of a slave, both of which should have ruled her out as Monarch, and so had uncertain legitimacy as a ruler in the eyes of her subjects. One of Nzinga's major legacies within the Mbundu region was she opened the door to other women rulers by proving herself capable of wielding power but her own reign was one where her legitimacy was constantly challenged which limited her options.

Nzinga first emerged in the Historical record in 1622 when she visited Portuguese Luanda as the emissary of her brother, the King, and publicly converted to Christianity, as many nobility in the region had done, to make a deal with the Iberians, this was after all only a year before the Iberian King would agree to never make slaves of a Christian African. Within two years, Nzinga's brother died under mysterious circumstances (he possibly killed himself or was possibly removed) and Nzinga took his place and worked with the Portuguese to strengthen her position, allowing them to send both missionaries and slave traders into her Kingdom in return for withdrawing soldiers from her borders, the deal she had agreed in 1622.

The relationship however, soured almost immediately. Portugal quickly went back on their promises both to withdraw soldiers from Nzinga's lands and to only trade in pagans. In turn Nzinga began to offer sanctuary for escaped slaves from Portuguese Lands, hoping to form a faction of clan-less followers who'd be loyal primarily to her. The Portuguese reacted by switching their support to a pretender and Nzinga responded to that by attempting to woo the Imbangala to switch sides from the Portuguese to her, a policy with only mixed success. A cold war of fighting for influence had started and it quickly became hot, by 1629 the Portuguese had invaded and driven her out of her native lands.

Nzinga regrouped and rebuilt her forces to the north east of her old territory, there she quickly expanded her reach by attracting followers and land from those looking for stability after the chaos of the Portuguese invasions. By the 1640s she controlled the largest state in the region, was allied with Kongo, the second largest, and had defeated the Portuguese in numerous battles. More than that, she had gained control over the exportation of slaves, and was able to divert them away from the Portuguese and towards instead her allies in the Dutch, who, after their aborted attempt in 1624, conquered parts of Angola in 1641. Nzinga did not reduce the amount of slaves though, the Dutch bought 13,000 slaves from her in 1643. This is another reason for having an uncertain legacy. She undoubtedly freed many slaves and accepted them into her court, and she worked to ensure the agreement ruling Christian Slaves as off limits was enforced, being in correspondence with Pope Alexander VII until 1661 but she also increased the supply of pagan slaves to the New World (famously selling many of the existing pagan religious hierarchy as slaves and using that money to build a church) in order to obtain goods with which to pay for Imbangala mercenaries to secure her position. It is possible that with the threat of the Portuguese removed, and mercenaries less vital, her attitude would change, she certainly took advice from ex-slaves but its equally possible it wouldn't.

The other difficult aspect of her legacy was that despite being well known for her opposition to the Portuguese, she did eventually make peace with them after her Dutch allies had been driven out of Luanda by a force from Portuguese Brazil. That treaty, much like the one she had agreed back in 1622, allowed missionaries and slave traders alike to roam her Kingdom at will and was bitterly resented as capitulation. Her Kingdom did not endure long after her death.

However given her stature, her religion, and the debates about Christian Slaves being held in Europe at the time, it is tempting to imagine that if she had driven out the Portuguese and both created a Christian united polity in Central Africa and enforced the agreement of 1623 banning the sale of Christians to the New World, this would massively reduce the amount of slaves sent to Brazil.

Below is one take on that scenario.


The incomparable Southwest African ruler Great Nzinga died peacefully in her sleep in 1663. She was eighty years old and had been bedridden with a throat infection that spread to her lungs. She was born into the royal family of Ndongo, a Mbundu kingdom in central West Africa, in around 1583. Her mother was one of her father's slave wives. During her thirty-seven-year reign, she fought for the independence and stature of her kingdoms against the encroachment of the Portuguese and the rapid growth in the African slave trade. Not only would she transform the region, but she would redefine the place of women in politics in Africa and the world.

At that time, the dominant central African kingdom was Kongo, and Nzingha was from the southwestern provinces of that rich civilization. She was taught to read and write Portuguese by visiting missionaries as the empire extracted slaves to work vast plantations in Brazil. Local black merchants and warriors, predominantly from the Imbangala and Mbundu tribes, supplied slaves to the Luanda and Benguela markets. They were rewarded with large profits and firearms.

Nzinga became Queen Regent after the death of her brother Mbandi. Forced out of the capital city of Kabasa, he had killed himself with poison out of despair, nominating Nzinga as his successor. The fortunes of the Ndongans only began to improve after the Dutch West India Company seized Luanda during the chaos of the Portuguese Restoration War. Through allyship with the Dutch and also the Imbangala, she was able to make military gains and establish a stronger new base in Matamba. The conquest of the neighbouring state of Kingdom of Matamba was her first step towards independence. The unity of the Ndongans triumphed over the division of the Europeans.

The Portuguese eventually returned to Luanda after the formal end of the Iberian Union. However, by then the Pope had recognized the independence of Ndongo and Matamba and Nzinga's forces were fortified with Dutch-supplied muskets and gunpowder. These forces policed the local merchants and warriors to intercept slave supply.

Nzinga would then begin her real work, teaming up with the Jesuit priest and missionary Antonio Ruiz de Montoya from Paraguay in order to convince the Catholic Church to issue a Papal bull fully ending the African Slave Trade. Montoya had laid a complaint before Philip IV of Spain as to the Portuguese policy of sending kidnapping expeditions into the neighbouring regions of South America. He subsequently obtained from the king important exemptions, privileges, and protective measures for the reductions of Paraguay. After this success, he headed to Southwest Africa rather than return to the Americas. This new proclamation rescinded the papal bulls issued by Nicolas V and while it did not stop the Slave Trade overnight, it was certainly the beginning of the end of the African Holocaust. The new papal bulls defended the rights of Christianized Africans and Native Americans, meaning that people could only be enslaved if not converted and must be freed upon conversion. Missionaries like Montoya worked feverishly to spread the word, and though much suspicion grew up whether conversions were genuine, the slave market collapsed as the prices for slaves skyrocketed. Nzinga, having seen slavery all her life, worked to revolutionize her own culture by ending the practice in her kingdom and uplifting the social status of women. While the Dutch were Protestants and thus as immune from papal bulls as they were Nzinga's edicts, market forces drove them out of the slavery business.

Instead, they and other European settlement strategies focused on colonization through corporations and indentured servitude for those willing to make the trans-Atlantic journey but without much capital beyond their own bodies. High-profit plantations were the gateway to colonizing the Caribbean and American South, but they proved to be their own end as servants whose contracts ended left to start their own competing farms. By the 1700s, middle-class farming outpaced the few huge plantations, which usually declined after a generation due to management. For example, George Washington left farming to focus on settlement schemes in Ohio, while the philosopher Thomas Jefferson retired to France and then London, unable to pay his debts and forfeiting his home at Monticello.



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