The Transatlantic Slave Trade

A graph illustrating the number of slaves that embarked on trans-Atlantic voyages between 1525 and 1875. They are grouped by the flag of the ships transporting slaves to the New World.

Economics of the Slave Trade

No exploration of maritime history in the early modern period would be complete without a look at the largest driver of maritime trade during the later part of this period, the trade in human slaves. The history of African slavery in the Americas began not long after the European discovery of the West Indies. Early Spaniards in the New World attempted to keep native Americans in slavery to work, both in mines and large-scale agricultural ventures, through the encomienda system, however this proved unsustainable given the unprecedented death rates among the natives. Instead the Spaniards (and soon the Portuguese) turned to the use of African laborers to work in the emerging sugar industry in the West Indies and Brazil (Wiesner-Hanks, 260).

    With the expansion of exploration and colonization by other nations in the Americas, the profitable slave trade exploded with most Western European nations taking part in the expansion of slave trading. The slave trade is often conceptualized in the simplified idea of the ‘triangular trade,’ a trading network that brought European manufactured goods to the West coast of Africa where European merchants exchanged these goods for slaves. These slaves were then carried across the Atlantic on a dangerous voyage that has become known as the infamous ‘Middle Passage’ on the way to the Americas. The final leg of this journey brought raw materials such as sugar or cotton from the new world back to Europe for the production of manufactured goods. Of course, unsurprisingly, this international trading network was much more complicated than this simplified triangle. There was tremendous trade within Europe during this time that was tangentially related to the slave trade. Iron, for instance, which was an important trade item for the English and Dutch in the slave trade, had to be sourced in Sweden or Germany, two areas that did not independently participate in the transatlantic slave trade but affected it through their metal exports (Evans & Rydén, 42). Inter-African trade was also common during this period with slave raiders often trading slaves over large areas, both along the coast, and from interior areas within the continent. Later, with the ascendance of the British colony in North America, and later the United States, the triangular trade began to look more like a square with the growth of industry in the Northeastern U.S. where ships were built, and perhaps more importantly, rum was made from the sugar brought up from the Caribbean before being shipped back across the Atlantic.

A portion of an iron slave shackle found on the Overtoom Plantation on the River Para in Surinam.

The Slave Trade and the Enlightenment: An Argument for Abolition?


In the 17th century, the Enlightenment burst forth on the stage of European Intellectual life. It was a movement that stood out from the Renaissance by its focus on breaking free of the past, looking for more reasoned answers to questions, both new and old (Wiesner-Hanks, 367). The Enlightenment led to discussions, debates, and the development of new ideas, particularly in the areas of politics, religion, and ethics. It was out of this age that we have inherited modern ideals of equality, democracy, secular states, and even gender parity (Taylor, 84). Slavery, and the slave trade, were vigorously debated topics during this period, with various philosophers discussing the morality of keeping slaves, and weighing it against the clear economic benefits of the slave trade for Europe. On the one hand, the rhetoric pursued by many Enlightenment thinkers was highly egalitarian such as Philosopher Marie Jean Antoine Nicolas Caritat’s calls for universal human rights, and language critical of the slave trade found in Denis Diderot’s Encyclopédie (Wiesner-Hanks, 383). Yet, on the other hand, many Enlightenment philosophers used the new ideas and reasoning techniques to cement support for slavery. David Hume, for example, asserted that scientific developments of the modern era had proved Africans to be inferior to Europeans given their geographical origins, which he used to justify their continued enslavement (Wiesner-Hanks, 387). Other philosophers during this period seemed uncomfortable with slavery, yet were unwilling to openly challenge the institution, or to call for the abolition of the slave trade. In perhaps his most famous work, Candide, Voltaire portrays slavery in its monstrous reality when his protagonist meets a Black man in Surinam who gives a very accurate description of what life is like for slaves in South America. “They give us one pair of linen trunks twice a year as our only clothing. When we work in the sugar mills and catch our fingers in the grinder, they cut off our hand. When we try to escape, they cut off our leg” (Voltaire, 81). Yet despite this blunt description of the institution, Voltaire was known for including racist comments in his other works and never publicly called for the abolition of slavery (Gordon, 13).

    Suppression of the Slave Trade began in the early 19th century, most notably with the British abolition of the trade in 1807, which they attempted to enforce throughout the entire Atlantic. All slavery was formally abolished in most European colonies during the 1840s. Interestingly, much of the impetus for abolition came not from Enlightenment leaders, but instead from religious groups. The movement was led largely by religious groups often considered on the fringe of society such as the Quakers and the Methodists who felt that Christian morals forbade the continuation of slavery; a consensus many Enlightenment thinkers, both Christian and secular, had failed to come to (Wiesner-Hanks, 526). Notably, the United States, a nation founded on Enlightenment principles, retained legal slavery in parts of the country until 1863, several decades beyond most European nations.