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01 / 05
Centers of Progress, Pt. 23: London (Emancipation)

Blog Post | Slavery

Centers of Progress, Pt. 23: London (Emancipation)

Introducing the city that helped to end the global slave trade.

You can read about other Centers of Progress in our book.

Today marks the twenty-third installment in a series of articles by HumanProgress.org called Centers of Progress. Where does progress happen? The story of civilization is in many ways the story of the city. It is the city that has helped to create and define the modern world. This bi-weekly column will give a short overview of urban centers that were the sites of pivotal advances in culture, economics, politics, technology, etc.

Our twenty-third Center of Progress is London during the late 18th and early 19th century, when the city played host to debates on the nature of human rights that would change the world. Today, we take the norm that no person can buy or sell another human being for granted, but it took humanity a long time to arrive at that norm. Slavery was accepted and rarely questioned for millennia throughout the world, but today slavery is illegal in all countries. Legal battles fought in London and legislative actions taken in London helped to end the global slave trade and bring about the dramatic change in attitudes about slavery—an invaluable victory for human freedom.

Today, London is a city that needs no introduction. It is well-known as one of the world’s foremost global cities as well as the capital and most populous city in the United Kingdom. London is recognized as a center of commerce, finance, the arts, education and research, and is among the globe’s most popular tourist destinations. It is home to Buckingham Palace, the iconic clock tower Big Ben, the British Museum, and Europe’s tallest Ferris wheel—the London Eye. It also houses four different UNESCO World Heritage Sites: Westminster Abbey, the medieval Tower of London, Kew Gardens, and Maritime Greenwich.

Evidence suggests that the site of present-day London has been inhabited since at least the Bronze Age. However, the site’s importance began when Romans founded a port settlement there in 43 AD. It was known as Londinium. Londinium soon became a regional trade hub, major road nexus, and the capital city of Roman Britain during most of the time that Romans ruled the province of Britannia. Once the Romans left Britain, Anglo-Saxons gained rule in London and the city became the capital of the eventual Kingdom of England. After the Norman conquest in 1066, William the Conqueror became the English king and it was during his rule that London was first linked to attempts to limit slavery.

In different parts of the world, slavery had long been subject to sporadic criticism, various limits and even brief bans. For example, Emperor Wang Mang banned slavery in China in 9 AD. It was reinstated soon afterward. In the 7th century, the Frankish Queen Balthild, herself a former slave, helped enact reforms that prevented the trade of Christian slaves. In the 740s, Pope Zachary banned the sale of Christian slaves to Muslims. And in 873, Pope John VIII similarly called the enslavement of Christians sinful and advocated for the slaves’ release.

But the early attempt to restrict slavery that would have the most lasting impact occurred in London. According to the Domesday Book, an extensive survey of England and parts of Wales completed in the 1080s, around 10 percent of people in the area were slaves. In 1080, William the Conqueror banned the sale of slaves to non-Christians. In 1102, the ecclesiastical Council of London banned the slave trade within England, decreeing “Let no one dare hereafter to engage in the infamous business … of selling men like animals.”

Within a generation, slavery had all but vanished in England. It was replaced by serfdom. Unlike slaves, serfs could at least own property. Also, they were not at risk of separation from their families. Alas, they could not move, since they were perpetually confined to the land they worked.  A feudal lord could sell that land, thus changing whom the serf served, but serfs themselves were not sold.

Since time immemorial, every major civilization practiced some form of slavery for most of history. Slavery has existed since at least 3500 BC, when the ancient Sumerians practiced it. Improvements in seafaring led to globalization of the slave trade. The Atlantic slave trade, for example, lasted from the 16th to the 19th centuries, and involved the transport of millions of sub-Saharan Africans across the ocean to live in bondage.

While the first foreign slave-traders in sub-Saharan Africa were Arab—Saudi Arabia, in fact, did not outlaw slavery until 1962—Europeans were soon prominent participants in the maritime slave trade, transporting roughly 11 million slaves out of Africa. The first and the worst offender was Portugal, which transported around 5 million slaves from the African slave markets mainly to its colony of Brazil.

Britain transported the second-highest number of enslaved Africans (2.6 million) to its various colonies. At least 300,000 African slaves were shipped to Britain’s North American colonies that would later become the United States. However, the near-total absence of slavery within Britain itself, which had persisted since the reforms of William the Conqueror, would prove critical to turning British hearts and minds against the institution.

As is widely known, the African slaves were treated as chattel rather than as people, and the conditions of the slave ships were horrific, with many enslaved people not surviving the journey. Most of those who made it through the voyage then lived the nightmare of forced, grueling agricultural labor on New World plantations. Slaves on the Caribbean and Brazilian plantations endured the worst conditions and suffered the highest fatality rates.

An enslaved Barbadian teenager, Jonathan Strong, was brought to London by his slave-master, who in 1765 beat Strong with a pistol and left him for dead in the street. Strong, bleeding and left mostly blind by the attack, ended up at a medical clinic for the poor held in Mincing Lane. There, as he received treatment for his wounds, Strong made an impression on the physician’s visiting brother—Granville Sharp (1735–1813).

Sharp, who was born in Durham but had lived in London since the age of fifteen, was forever changed by the encounter. He and his brother took Strong to a hospital and paid for the latter’s months-long treatment there. But not long after becoming well enough to leave the hospital, Strong was recaptured by his former enslaver, who attempted to sell Strong to a Jamaican plantation.

Sharp successfully defended Strong’s freedom, defeating Strong’s former slave-master in court—but only on a technicality. Tragically, Strong’s health was permanently damaged from the pistol attack and he passed away at the age of 25 in 1770. Sharp devoted himself to bring about a definitive legal ruling on the question of whether a man could be compelled to leave Britain and enter slavery, and his efforts earned him a reputation as an Enlightenment thinker and anti-slavery campaigner. He was not alone. The abolition movement in Britain was growing.

In 1769, another slaver from the colonies attempted to bring an enslaved man, James Somerset, to London. In 1771, Somerset escaped. In less than two months, Somerset was captured and arrangements were made to sell him again into slavery in Jamaica. Three Londoners applied for Somerset to receive a hearing, and their petition was granted. Many concerned Britons sent money to launch a legal defense for Somerset, but several lawyers volunteered to do the case pro bono. Sharp advised Somerset’s lawyers extensively.

One barrister, William Davy, famously cited in Somerset’s defense an alleged 1569 case in which a cartwright attempted to bring a slave to England from Russia. In that case, it was resolved that England’s air was “too pure” for a slave to breathe and that anyone in England was therefore free. Or, as the London-born jurist Sir William Blackstone (1723–1780) had once put it, “The spirit of liberty is so deeply ingrained in our constitution that a slave, the moment he lands in England, is free.”

Somerset won his case. The ruling stated that, while in Britain, Somerset was free. Furthermore, he could not be forced to depart the country. The ruling was a turning point.

Regardless of William the Conqueror’s original motivations behind limiting slavery, by the time of the Somerset judgment, the absence of slavery in Britain had become a matter of British pride. It was also a moral issue among several Enlightenment thinkers, members of the clergy—including Anglican cleric John Newton (1725–1807), the writer of the well-loved hymn “Amazing Grace”—and the general public.

By 1807, thanks to mounting public pressure and the work of tireless reformers such as William Wilberforce (1759–1833) in Britain’s London-based parliament in Westminster, Britain banned the international slave trade with the Slave Trade Act. When diplomatic efforts to pressure Paris and Vienna to sign similar legislation proved futile, public support for the use of force rose.

Decision-makers in London ordered the British Navy to form the West Africa Squadron in 1808 to blockade West Africa and stop the movement of slave-transporting ships across the Atlantic Ocean. By the 1850s, the West Africa Squadron consisted of approximately 25 ships, two thousand British men and a thousand additional crew members who were recruited locally, mainly from what is now Liberia. The British naval officers were paid a reward for each slave that they freed, but the main incentive was humanitarian—by that point, anti-slavery efforts were hugely popular in Britain. As the poet Alfred Tennyson (1809–1892) put it, “This spirit of chivalry… we see it in acts of heroism by land and sea, in fights against the slave trade.”

Between 1808 and 1860, the West Africa Squadron successfully hunted down at least 1,600 slave ships and freed around 150,000 African slaves. Spain and Portugal attempted to continue the slave trade, often purchasing slaves from African sellers. In the mid-18th century, King Tegbesu of Dahomey in present-day Benin drew the equivalent of around 250,000 pounds annually—the greatest part of his income—selling slaves captured in battle to Europeans. His successor to the throne declared in 1840 in response to British pressures to stop selling slaves, “The slave trade is the ruling principle of my people. It is the source and the glory of their wealth… the mother lulls the child to sleep with notes of triumph over an enemy reduced to slavery.” His acceptance of slavery demonstrates how deeply the practice was still ingrained at the time, across the globe.

The British Navy eventually blockaded Brazil as well and succeeded in halting the Brazilian slave trade in 1852. But the effects of the abolition movement that started in London did not stop there. The movement saw a revival in the 1860s, when David Livingstone, the Scottish physician and prominent member of the London Missionary Society, published reports describing the Arab slave trade in Africa that too moved the British public. In the 1870s the British Navy again devoted resources to stopping the slave trade—this time by traders based in Zanzibar. Thanks in part to efforts launched in London, the number of countries with legal slavery plummeted throughout the 19th century.

While the lawmakers of London during the 18th and 19th centuries were far from perfect, their anti-slavery zeal helped to change the world for the better. As the Irish historian William Lecky (1838–1903) put it, “The unweary, unostentatious, and inglorious crusade of England against slavery may probably be regarded as among the three or four perfectly virtuous pages comprised in the history of nations.”

It was in London that British abolitionists organized, won court and legislative victories, launched naval ships with the mission of emancipating slaves, and ultimately helped to alter moral norms that had persisted since the dawn of civilization. For its critical role in ending the slave trade and de-normalizing the institution of slavery, London is justly our twenty-third Center of Progress.

Reuters | Trade

European Council Gives Nod to Mexico Free Trade Deals

“The European Council on Monday gave the green light for the European Union to sign ​two deals governing trade, security and cooperation between ‌the European Union and Mexico…

The Interim Trade Agreement (ITA) would remove ​tariffs on goods such as EU agri-food exports and boost raw materials ‌cooperation ⁠while the Political, Economic and Cooperation Strategic Partnership Agreement (MGA) comes into effect.”

From Reuters.

Blog Post | Trade

Make Trade, Not War: How Free Exchange Creates Peace

Open markets lead to closed battlefields.

Summary: Trade does more than increase economic prosperity—it also fosters peace. By strengthening economic interdependence and aligning material incentives, trade reduces the likelihood of both interstate and civil conflict. A growing body of empirical research shows that open markets and cross-border exchange act as powerful constraints on violence, complementing or even surpassing the effects of democratic institutions.


In earlier essays, I argued that trade makes us richer, more trusting, more honest, more fair, and more tolerant. In this final essay, I will show that trade also promotes peace and mitigates the outbreak of war. Distrust, corruption, unfairness, and intolerance can often erupt into violence. By undermining these less-than-desirable attitudes and behaviors, trade can help reduce violence as well. But it may be even more straightforward than that: it’s simply not a good idea to maim or kill your customers or suppliers. War is bad for business. When you rely on others to buy your product or supply your needs, rocking the relational boat seems suboptimal. As economist Christopher Blattman wrote in his book Why We Fight,

Interdependence doesn’t eliminate the risk of war. There could still be a commitment problem, uncertainty, or unchecked leaders that push our two groups to fight. But because of entwined material interests, these forces must now overcome even more powerful incentives for compromise than usual. The gravitational pull of peace has grown stronger.

In The Better Angels of Our Nature, Harvard’s psychology professor Steven Pinker documented the worldwide decline in violence throughout history. One major contender for the driver of this more peaceful trend is known among international relations scholars as the democratic peace theory. As explained by Pinker, “Democratic government is designed to resolve conflicts among citizens by consensual rule of law, and so democracies should externalize this ethic in dealing with other states.” Trust in the procedures of democracy consequently builds trust between democratic governments. “Finally,” Pinker notes, “since democratic leaders are accountable to their people, they should be less likely to initiate stupid wars that enhance their glory at the expense of their citizenries’ blood and treasure.”

While the liberal peace theory remains influential, a growing wave of empirical research over the last three decades suggests that markets may play a bigger role than the ballot box. This shift in consensus toward what’s known as the capitalist peace theory posits that trade openness and economic interdependence are among the primary forces that mitigate war. Of course, scholars continue to debate over how much trade and economic freedom contribute to peace. But liberal peace theorists now include economic interdependence as an essential element within the broader liberal peace project. Economic interdependence is “part of the glue that cements the ‘liberal peace’ together.” As trade has grown worldwide, so has peace (see Figures 1 and 2).

Figure 1. Growth in Global Trade

Source: Esteban Ortiz-Ospina, Bertha Rohenkohl, Veronika Samborska, Simon Van Teutem, Diana Beltekian, and Max Roser, “Trade and Globalization,” Our World in Data (December 2025): https://ourworldindata.org/trade-and-globalization

Figure 2. The Rate of Wars Worldwide

Source: Bastian Herre, “How Different Measures Capture How Common and Deadly Conflicts Are, and When to Use Which One,” Our World in Data (July 6, 2023): https://ourworldindata.org/conflict-measures-how-do-researchers-measure-how-common-and-deadly-armed-conflicts-are. The rate is calculated by dividing the number of wars by the number of all states.

French economist Frédéric Bastiat wrote that trade barriers “create isolation, isolation gives rise to hatred, hatred to war, war to invasion.” And an abundance—and I do mean abundance—of empirical studies have shown Bastiat to be correct: trade indeed reduces interstate military conflict (see Figure 3). Other studies further solidify the adversarial relationship between trade and international violence: while trade reduces conflict, international conflict in turn reduces trade. One pair of scholars put it succinctly: “The positive relationship between economic interdependence and peaceful relationships is so well established that research now focuses on the conditions that cause variations.”

Figure 3. Trade and the Reduction of Conflict

Source: Julian Adorney, “Want Peace? Promote Free Trade,” Hinrich Foundation (September 10, 2020): https://www.hinrichfoundation.com/research/article/trade-geopolitics/trade-and-peace. Based on data from Patrick J. McDonald, “Peace through Trade or Free Trade?” The Journal of Conflict Resolution 48:4 (2004): 547-572.

Of course, these conditions and variations matter. For example, one study in the Journal of Conflict Resolution found that trade overall reduces conflict, but the pacifying effects vary by industry: trade in manufactured goods has a stronger pacifying effect than agricultural trade or trade in raw materials. Thus, trade in some industries yields more peace than others. Also, mere membership in the General Agreement on Tariffs and Trade or the World Trade Organization does not appear to reduce conflict. Countries must actually trade.

Civil war is also less likely to break out where trade is present. A 2012 study controlled for a number of variables, including income per capita, growth rates, total population, ethnic fractionalization, and oil exportation. It found that higher levels of economic globalization—including foreign direct investment, portfolio investment, import barriers, tariff rates, and the overall extent of trade—reduce the risk of civil war. A 2016 study demonstrated that secure property rights, high-quality legal institutions, sound money, and free trade lower the probability of civil war. Covering the period between 1970 and 1999, political scientists Katherine Barbieri and Rafael Reuveny found that international trade, foreign direct investment, and foreign portfolio investment reduce the risk of civil war in all states observed.

As is well known, civil wars are more likely to take place between different ethnic groups. In many cases, ethnic groups silo themselves off from one another, escalating distrust and hostility toward out-groups. Trade barriers play a role in this siloing. It turns out that barriers to trade entry can produce what economist Saumitra Jha has labeled as ethnic cronyism: a set of “ethnic trading networks” often “based upon personal and community ties.” Jha’s analysis of South Asian medieval ports demonstrated that trade and low barriers to trade entry made these areas five times less prone to religious rioting between Hindus and Muslims in the period from 1850 to 1950. During the same period, these areas were 25 percentage points less likely to experience any religious rioting. Between 1950 and 1995, these areas were still less than half as likely to experience ethnic rioting.

Violence does not mean traditional interstate or civil wars alone; it often begins with how states treat their citizens. The closing and centralization of the economy is, to borrow from economist Don Lavoie, the militarization of the economy. Militarized central planners tend to wage war on their own citizens. Crucially, trade openness acts as a check on this central power, keeping potentially violent governments at bay.

Barbara Harff, a leading expert in the study of genocide and political mass killings, examined incidences of genocide between 1955 and 1997. One factor that decreases the risk of political mass murder, she found, is economic interdependence. Political scientist Clair Apodaca has also shown trade to be “advantageous to guaranteeing human rights,” with foreign direct investment being “favorable for human rights.” Emilie M. Hafner-Burton of UC San Diego summarized the state of the scholarship well: “One of the key discoveries of the past few decades is that it is possible to promote human rights by encouraging economic openness and growth through trade and investment…Market-oriented economic development…is correlated with better protections for human rights.”

Over two centuries ago, German philosopher Immanuel Kant wrote, “The spirit of trade cannot coexist with war, and sooner or later this spirit dominates every people. For among all those powers (or means) that belong to a nation, financial power may be the most reliable in forcing nations to pursue the noble cause of peace[.]” Others echoed this sentiment. “PEACE,” Montesquieu argued, “is the natural effect of trade.” In Rights of Man, American revolutionary Thomas Paine described commerce as “a pacific system, operating to unite mankind, by rendering nations, as well as individuals, useful to each other…If commerce were permitted to act to the universal extent it is capable of, it would extirpate the system of war, and produce a revolution in the uncivilized state of governments.”

These philosophers and revolutionaries were correct. In the end, trade steers us away from war and brutality and toward peaceful cooperation. If we care about a future that is richer, freer, and more humane, then keeping markets open and people connected through trade is one of the surest paths to a more peaceful world.

Reuters | War

Congo, M23 Sign Framework for Peace in Qatar

“The Democratic Republic of Congo and the M23 rebel group signed on Saturday a framework agreement for a peace deal aimed at ending fighting in eastern Congo that has killed thousands of people and displaced hundreds of thousands more this year.

The agreement was signed by representatives from both sides at a ceremony in the Qatari capital Doha.

It was the latest of several documents that have been signed in recent months as part of efforts, backed by the United States and Qatar, to end the decades-long conflict in Congo that has often threatened to escalate into a full-blown regional war.

The framework was described by U.S. and Qatari officials as an important step to peace but one of many that lie ahead.”

From Reuters.

The Hindu | War

Maoists Seek Peace Talks with Chhattisgarh Government

“A purported letter of the banned Communist Party of India (Maoist), offering to give up arms in view of the changed world and country’s circumstances, albeit with certain conditions, appeared in Chhattisgarh on Tuesday (September 16, 2025)…

‘In order to take forward the process of peace talks, we are making it clear that, in view of the changed world and country’s circumstances, as well as the requests made by the Prime Minister, Home Minister and senior police officers to give up arms and join the mainstream, we have decided to give up arms. We have decided to declare a temporary halt to the armed struggle. In future, we will fight with all political parties and struggling organisations on public issues,’ the letter read.

It added that the banned outfit was ‘ready to talk to the Union Home Minister or persons appointed by him or a delegation on this subject’.”

From The Hindu.