Slavery was a socially accepted and promoted practice in Greek and Roman antiquity and in Eastern empires. The modern practice of human trafficking is another iteration in the history of the international slave trade. An intricate global network connected traders in Africa to merchants in emerging European countries, as well as buyers in the Americas. Warring states enslaved surviving opponents and kidnapped people from other states to provide bodies for slavery. Trade expanded when Portugal and other European powers built large fleets capable of sailing to Africa and trading with merchants involved in the Arab and African slave trades. Spanish explorers imported West Africans to the Americas, establishing a practice that lasted for over three centuries. Historians estimate that 11 million slaves were transported from Africa to the Americas, and over one million died from violence, smallpox and other fatal diseases during the tumultuous journey across the Atlantic known as the Middle Passage. An estimated total of 25 million Africans were removed from the continent and sold into slavery.

Many African kingdoms also practiced local forms of servitude, and self-interested African merchants and rulers sold humans to European merchants before demand from slave labor reached the point that European powers conducted slave raids. Colonialism buttressed by a racial ideology that touted the superiority of Europeans to Africans and other non-white races grew concomitantly with the burgeoning slave trade. Empires and kingdoms required free labor to expand and maintain their global presence, and improved maritime and navigational skills buttressed their expansion. The historical human mass displacement has resulted in global diasporas serving as remnants of a once powerful institution.

Abolishing Slavery

Harnessing the momentum of the Enlightenment and revolutions, Western European powers began formally abolishing slavery within their empires. Despite exploiting the slave trade for two centuries, Great Britain eventually heralded a strong anti-slavery tradition that included the formation of abolitionist societies and multiple efforts to push legislation through Parliament to ban slavery outright. Late eighteenth and early nineteenth century efforts to ban the slave trade faced stiff resistance from the East India Tea Company, merchants, plantation owners in the Americas and throughout the empire. By 1807, the Slave Trade Act banned the slave trade within the British Empire and the 1833 Slavery Abolition Act, coinciding with a slave rebellion in Jamaica, emancipated slaves through the empire. Parliamentary acts resulted from social and moral campaigning and through pressure by abolitionist MPs, Quakers and women. Britain combated the slave trade by crafting treaties first with individual European countries and then African and South American countries, bolstering its efforts by creating an Anti-Slavery Squadron and influencing countries to ban slavery.

Following the French Revolution, France banned slavery, but Napoleon Bonaparte swiftly reinstated it in order to support an expanding empire. Canadian colonies and smaller European kingdoms also abolished slavery in the late eighteenth and early nineteenth centuries.

Slavery in the US

Although many important political figures in the early US owned slaves, some of the founding fathers expressed uneasiness regarding the “peculiar institution” of slavery. The slavery issue predated the formation of the nascent US, as the British Royal Army offered slaves freedom during the Revolutionary War if they fought against the colonists. Thomas Jefferson had authored a passage in the Declaration of Independence condemning slavery in the future country, but delegates from South Carolina and Virginia obstructed its approval. The Northern colonies, such as New Jersey, Rhode Island, Massachusetts, Connecticut and New Hampshire, instituted a gradual process of abolition in the late eighteenth century that began with the liberation of slave children and culminated with full emancipation. Their legislative efforts to eliminate slavery contrasted with the strengthening of the practice in southern states and western territories that became candidates for statehood. President Jefferson signed the Act Prohibiting Importation of Slaves in 1807, deeming trade as piracy punishable by death. This act referenced Article I of the US Constitution, which guaranteed that the slave trade would be protected for twenty years.

The concept of manifest destiny encapsulated a slavery versus anti-slavery dichotomy that divided established northern and southern states over which new states could legally practice slavery. Kansas [PDF] held a popular vote to decide the issue, and slaveholders from nearby states rode into the state to cast ballots in favor of slavery, resulting in Kansas being admitted as a slave state. Congress enacted the Missouri Compromise of 1820 in an attempt to resolve in which newly settled territories slavery could be practiced. The Compromise balanced the number of slave and non-slave states by admitting Missouri as a slave state, Maine as a non-slave state and prohibiting slavery in the Louisiana Purchase territory north of the parallel 36°430′ north, except for Missouri. The number of pro-slavery and anti-slavery states bore importance to representation in Congress, as an imbalanced ratio stoked fears on both sides. The compromise illustrated the precarious balancing act of the political consensus leading up to the Civil War. The consensus as encompassed in the Missouri Compromise withered through the Dred Scott decision, formation of anti-slavery political factions and the abolitionist movement, leading to the secession of 11 states to form the Confederacy followed by the bloodiest war in American history. The Civil War lasted from 1861 until 1865, devastated portions of the country and resulted in the Civil War Amendments. The Thirteenth Amendment abolished slavery, the Fourteenth Amendment guaranteed citizenship for freed slaves and the Fifteenth Amendment ensured voting rights for all male citizens.