Most introductory resources, especially written from a Christian perspective, will tell you that slavery virtually disappeared in medieval Christendom. In the late Roman Empire, up to 20 percent of the population may have been enslaved, or as many as 9.65 million souls, although other estimates put the percentage much higher. Over the next few centuries, this vast slave population transitioned into a new class within medieval society.
Many materials from a Christian perspective will hint that this came about through the influence of the gospel. Good reason to pat ourselves on the back? Not so fast.
The Serf System
First, the slaves of the Roman Empire were never fully emancipated as a class. Indeed, in the Eastern Roman, or Byzantine Empire as it’s known today, slavery continued to be practiced up until the Empire’s fall in 1453. Meanwhile in the west, the slave system was gradually replaced by the serf system.
Medieval society largely consisted of the knightly/warrior class, the priestly/churchman class, and the peasant/commoner class. Peasants, while often poor and suffering from legal discrimination, had opportunities to rise in the world. They were able to join the church. They could be knighted, although this became less common from the middle of the twelfth century. As townsmen, they might grow rich as merchants and influential as aldermen or burgesses. But for the serfs, it was a different story.
While the practice varied in detail from place to place, serfdom was legally signified by three things: chevage, mainmort, and formariage. Chevage was a head tax payable as a sign of servile status. Formariage was the payment a serf must make to his lord if he wished to marry a serf belonging to another lord. Mainmort meant that legally speaking, a serf had no right to pass an inheritance to his family after his death: his lord was his heir, though in practice the lord often claimed only the best cow or pig as a sign of his right to the whole.
Serfs were also tied to the land. If land was sold or ceded by one lord to another, the serfs would be bought or ceded right along with it. They were required to perform corvees, or unpaid servile labor, on the lord’s manor, fields, mines, roads, or forests. In addition, a large percentage (up to 50 percent) of the serf’s own crops each year could be taken by the lord. Many other legal handicaps also existed: for example, even where there were laws against the rape of a serf, the penalty was no more than a light fine.
While still keeping thousands in a state of servitude, the serf system must have been preferable to the Roman-style chattel slavery which it replaced. But this substitution was not comprehensive. Chattel slavery also persisted throughout the medieval period. Western merchants kidnapped and sold Christian boys at a vast profit to the Moors in Spain, for example, operating out of the slave market at Verdun in northern France. “Despite repeated papal decrees against the trade, Christian merchants refused to give up the lucrative business of enslaving, castrating and selling young men,” Judith Herrin reports, further noting that Rome itself hosted a major slave market.
Chattel slavery also persisted at manors and in workshops throughout northwestern Europe. The victims were primarily women, known as ancillae. Roman law provided that women would pass on their servile status to the heirs of their bodies, so these women and their offspring were items of property to be bought and sold. The laws concerning their rape were aimed not at protecting the women, but at enabling a master to prosecute someone else’s trespass on, or damage of, his property. Ancillae did not ordinarily marry, and although they were clearly vulnerable to their masters’ lusts, it was they who bore the blame and gained a reputation for concupiscence.
Although the land-based feudal economy of medieval Western Europe made male slavery economically unviable, ancillae were still valuable as domestic slaves in great manorial houses, as skilled workers in textile workshops, or as beasts of burden within cities, hauling heavy loads up and down hills or staircases. More docile and easily managed than their male counterparts, and constantly under the eyes of their owners, ancillae had little chance of escape from a lifetime of repetitive toil.
Slavery in the Crusader States
While chattel slavery was largely impractical in Western Europe, the economic situation was quite different in the Frankish crusader states (A.D. 1099-1291) where slavery was both convenient and profitable.
Prisoners of war or the Saracen inhabitants of conquered towns were liable to be captured and enslaved by the crusaders. The Moorish traveler Ibn Jubayr, during his visit to the kingdom of Jerusalem in the early 1180s, described seeing chain gangs of both male and female Muslim slaves on the roads. Just a few years later, in 1187, as Saladin reconquered much of the kingdom, his chroniclers claimed that he had freed between nine thousand and twenty thousand Muslim slaves.
The customary law of Frankish Jerusalem provided that a slave must be freed if he converted to Christianity, but in practice many slave owners found ways to circumvent the law. Some refused to allow their slaves to be baptized, while other refused even to let them hear Christian sermons. In 1237, accordingly, Pope Gregory IX came up with a solution: slaves must be allowed to convert, but would remain slaves.
The Templars employed Muslim slaves in building projects, and in the thirteenth century shipped many of them west to work on their substantial holdings in Sicily and Apulia. This was not merely because they had a surplus of prisoners of war and no easy way to deal with them. Prisoners of war could usually be exchanged without too much trouble.
In 1263, the chronicler known as the Templar of Tyre tells us that the Egyptian sultan Baibars offered to exchange his Christian prisoners for Muslim captives held by the Templars and Hospitallers. The military orders refused, saying that “their slaves were of great profit to them, for they were all craftsmen and it would have cost them dearly to hire other craftsmen.” Baibars, a bloodthirsty tyrant himself, was amazed by their refusal even to take pity on the Frankish prisoners in Saracen hands.
Nor was the Templar interest in slaves limited to Saracen prisoners of war. During the 1270s and 1280s, the Templars established a wharf in the busy Cilician shipping town of Ayas, which became a hub for the trade of Russian, Circassian, and Greek captives as well as Turks and Arabs.
The Renaissance of Slavery
By the 1300s, the Italian city-states of Venice, Genoa, Pisa, Florence, and others had succeeded in opening the whole Mediterranean to trade. Meanwhile, the serf class was gradually dwindling in most of Europe, a process hastened by the arrival of the Black Death in 1348. When the plague arrived in Florence, more than half the population died and the plague victims were predominantly from among the lower classes, already weakened following a severe famine the previous year. A manpower shortage followed, and in 1363 Florence responded with an edict that permitted unlimited importation of foreign slaves, provided that they were not Christians.
If the decline of serfdom created the demand for slaves, supply came through the Italian merchants via the Black Sea and the Eastern Mediterranean. In this period many of the slaves were Tartars (or Mongols), but Ethiopians and Moors were also traded, along with Russians, Greeks, and Circassians. “Every prosperous noble or merchant had at least two or three of them; many had more,” says Iris Origo of the slaves in Tuscany, which the poet Petrarch called “the domestic enemy.”
Slavery sat uncomfortably on the consciences of many people. Devout Venetians were unwilling to face God as slave owners, so many of them wrote wills providing for the emancipation of their slaves after their death. But the church did little to protect slaves during the lifetime of their masters. Origo explains:
The Catholic Church—starting from the premise that all human institutions were merely remedies for sin, and that maladies inherent in the social structure could not be eradicated without danger to the whole—tolerated slavery as a necessary (and indeed, not very important) evil. Christian masters were urged to be merciful; but to the Christian slave the chief consolation offered was that which Seneca had already given to the Stoic: that bondage could only enslave the body, not the soul. “Not circumstance, but sin, makes us slaves; not enfranchisement, but inner perfection, makes us free.”
Renaissance slavery could be brutal, especially for female slaves. One insurance policy taken out on a slave in transit stated the insurer’s willingness to bear the risks for acts of God, perils of the sea, and men of war, but not attempts at escape or suicide: “if she throws herself into the sea of her own accord.” This was clearly common enough to be taken into account by the canny insurer, and female slaves had to cope with a great deal of trauma. Rape and ensuing pregnancy were common even though a pregnant slave was almost worthless. On her arrival in Genoa, one pregnant slave claimed that her previous owner in Majorca was responsible for her condition. Her new owner contacted Majorca, and received the following reply:
We have spoken to the cappellano to whom your slave belonged and he says you may throw her into the sea, with what she has in her belly, for it is no creature of his. And we believe he is speaking the truth, for if she had been pregnant by him, he would not have sent her. He says that it belongs to a nephew of his, who had a great quarrel about this slave. So that he does not want her back here on any account. We think you had better send the creature to the hospital.
While slavery was never as commonplace in medieval Christendom as it was in the late Roman Empire, it was never entirely eradicated—and where it was mitigated or partially transformed, the main motive seems to have been economic pragmatism, not true compassion. Wherever it was convenient or profitable to own slaves, the medievals bought, sold, and exploited them.
Medieval slavery differed from American slavery primarily because it was justified by classism rather than racism. Christian nobles in the Crusader states seem to have felt far more in common with Muslim leaders, whom they viewed as being of the same social status, than they did with their own Christian serfs or peasants. While it was not unheard-of for men of the peasant class to attain knighthood or nobility, such people faced intense prejudice and even hatred in the high and late middle ages. In a poem lamenting the fall of Acre in 1291, the Templar of Tyre identified one reason why he believed God had judged Christendom:
And though we are all creatures
Of God, still it is not right
That all should have the same status.
It was by the Will of God,
That Abraham placed Ishmael
Beneath the feet of Isaac, who though younger,
Was begotten of the lady wife.
Ishmael was considered a serf,
For he was a bastard, born of a serf-girl.
By the 1600s, when chattel slavery was introduced to the American colonies, the intellectual foundations for the medieval caste system seem to have crumbled before the Reformation doctrine of the priesthood of all believers. For whatever reason, the new justification of racism was required in order to justify the new chattel slavery.
In many other ways, medieval and American slavery were startlingly alike. Both drew on the same tradition of Roman civil law. Both, after a brief hesitation over the idea of enslaving fellow Christians, quickly overcame their scruples. Both turned a blind eye to the Exodus 21:16 prohibition of man-stealing among other slavery provisions in God’s law. Both rendered women vulnerable to rape with no hope of justice. And both were tolerated and even justified by the church of their day.
Did medieval practices influence American slavery? Did medieval justifications and excuses get recycled in the 1600s as American slavery was getting started? Certainly, there were echoes of Ambrose of Milan’s words as quoted by Origo above: “Not circumstance, but sin, makes us slaves; not enfranchisement, but inner perfection, makes us free.”
This ought to be a sobering warning to us today. Medieval and Renaissance slavery was nowhere near as prevalent as American slavery was, and because its victims included people of a wide variety of ethnicities, it didn’t result in the same kind of institutionalized racism. Nevertheless, in some sense the medievals can be held responsible for what happened in America later on. If they had dealt truthfully with the slavery question in their own day, if they had applied God’s law to slave traders and their victims, then it’s not a huge leap to imagine a very different version of American history.
The medievals did not sin as outrageously as their American descendants, but they never repented. The church never uprooted the legal foundations laid by the classical pagan world that came before them. And its failure to do so left the doors wide open for much, much worse.
 Kyle Harper, Slavery in the Late Roman World, A.D. 275–425 (Cambridge: Cambridge University Press, 2011), p. 59.
 John France, Western Warfare in the Age of the Crusades, 1000–1300 (Ithaca, NY: Cornell University Press, 1998), p. 55.
 France, p. 75.
 Christopher MacEvitt, The Crusades and the Christian World of the East: Rough Tolerance (Philadelphia, PA: University of Pennsylvania Press, 2007), pp. 145–149.
 Stephen P. Pistono, “Rape in Medieval Europe” in Atlantis Vol. 14 No. 2 (1989), p. 39.
 Judith Herrin, Byzantium: The Surprising Life of a Medieval Empire (London: Penguin Books, 2008), Ch 15. Venice also hosted a major slave market, though according to Thomas Madden (see n. xii), it was closed in 1366.
 Susan Mosher Stuard, “Ancillary Evidence for the Decline of Medieval Slavery” in Past and Present No. 149 (1995), pp. 3–28.
 France, p. 233.
 Benjamin Kedar, “The Subjected Muslims of the Frankish Levant”, in J. M. Powell (ed.), Muslims Under Latin Rule 1100–1300 (Princeton: Princeton Legacy Library, 1990), pp. 135–174.
 Malcolm Barber, The New Knighthood: A History of the Order of the Temple (Cambridge: Cambridge University Press, 1994), p. 240.
 Iris Origo, “The Domestic Enemy: The Eastern Slaves in Tuscany in the Fourteenth and Fifteenth Centuries,” in Speculum Vol. 30 No. 3 (1955), pp. 321–326.
 Thomas Madden, Venice: A New History (London: Penguin Books, 2012), p. 278.
 Origo, p. 323; the quotation is from Saint Ambrose, Epist. CI, p. 37. (Editor’s note: here it is easy to see how the dangerous legacy of Neoplatonic thinking undermines morality under cover of facile pretexts and sophistry.]
 Origo, p. 332.
 Paul F Crawford (trans.), The ‘Templar of Tyre’: Part III of the ‘Deeds of the Cypriots’ (New York, NY: Routledge, 2016).
 Joel McDurmon, The Problem of Slavery in Christian America (Powder Springs, GA: The American Vision, 2017) is a detailed and convincing study of American slavery.