adultery, prostitution, and robbing owners of their slaves (mainly by aiding fugitives). Valencia’s chief bailiff (bayle general) and his staff had responsibility to sell other slaves that came to be owned by the Crown. These were generally recaptured runaway slaves or transgressors such as vagabonds, unlicensed beggars, and convicted adulterers, whose crimes were punished by enslavement.4
Free-born people could become slaves in limited and statistically insignificant ways at different periods. In Roman times, destitute parents could resort to two methods for disposing of children they could not support. Parents could sell their children as slaves, though the practice was illegal. Or they could abandon unwanted infants, a process euphemistically called exposure. Not all the abandoned children died, as each locale had well-known places where parents left their unwanted infants, who could be rescued and raised either as slaves or as free persons.
In some periods, violations of law and custom could lead to enslavement for the guilty, but the numbers of slaves produced as a consequence of such actions were probably small. In the Visigothic kingdom, penal slavery was a mandatory penalty for certain offenders: rapists of free women, adulterous wives, those who induced abortions by drugs, kidnappers of free children, forgers, and counterfeiters. Public crimes, such as failure to come to the aid of the king in wartime, carried the possibility of enslavement to the royal treasury or to a person the king designated. Mistresses of clerics could, in certain circumstances, be sold into slavery by the local bishop.5 In later periods, Christians who aided the Muslims by providing them with naval stores or ships or who navigated Muslim ships were to be enslaved when captured, according to a thirteenth-century Castilian law code.6
One special category of judicial enslavement could be seen in the Crown of Aragon, when in the fifteenth-century communities of Muslims (Mudejars) and Jews lived under their own authorities, who could judge the conduct of the members of their own community and punish transgressors. The Christian monarchs did impose certain limitations. Muslim and Jewish judges could not enforce the death penalty or corporal mutilation on convicts, even though their own law codes called for such penalties. In such cases, the guilty persons fell under royal jurisdiction and became slaves of the Crown. They could be sold or granted in turn to private Christian owners whom they would serve as slaves.7
Spanish judicial authorities during the early modern period sentenced convicts to duties deemed necessary for the state but considered too dangerous or difficult to attract free labor. The categories included galley service, mining, presidio service, naval arsenals, and public works. Convicts provided most of the laborers in these endeavors, but their numbers were almost always insufficient. At times, slaves were used to make up the full work force. The term “galley slave” is so common that we tend to believe that all rowers on galleys were always slaves. That is not true. Free, salaried oarsmen provided the crews of the galleys during the Middle Ages. The practice of sending convicts to row began under Fernando and Isabel at the end of the fifteenth century, and these forzados gradually replaced the free oarsmen over the course of the sixteenth. An increasing number of crimes were punished by condemnation to the galleys, and by the late sixteenth century penal servitude in the galleys had become the usual fate for convicted commoners. Convicted criminals from the nobility and the clergy were usually exempt, but the clergy who committed capital crimes could end up in the galleys.8
Forzados alone could not fill the demand for galley rowers, despite the increasing number of crimes punishable by galley service and despite the increasing rate of convictions. Their numbers consequently came to be supplemented by slaves from several other sources. Many were Muslim prisoners of war, captured in naval engagements in the Mediterranean and in attacks on North African cities. Other ways for slaves to enter galley service was for forzados to purchase slaves who would substitute for them, or to provide money for such purchases. Government officials bought others, almost always Muslims, from private owners, frequently using the profits from the auctions of overage or disabled galley slaves. Slave owners, by selling or donating recalcitrant slaves to the royal officials for galley service, rid themselves of unsuitable slaves and perhaps ensured the loyalty of their remaining slaves, who no doubt hoped to avoid a similar fate.9 As an example, in 1603 the Spanish government paid don Diego López de Haro two hundred ducats as the price of two Turkish slaves whom he sent to the galleys.10 The government could confiscate privately owned slaves for galley service in times of heightened demand for galley rowers or at periods when private owners offered an insufficient number for donation or sale. In galley service, forzados could only work at the oars. Slaves might man the oars as well, but they could occupy other positions prohibited to the forzados, such as assistants of the guards and barbers and servants of the officers of the vessels.11
Two special categories existed among the slaves on the galleys. One group, the arráeces—usually the captains of Muslim pirate vessels—were held as slaves permanently. They had no hope of being sold away from the galleys or of being freed. The other group was slaves who were sentenced to the galleys after having been convicted of a crime. During the term of their sentence, they blended into the mass of the forzados. When their sentences expired, they did not attain their freedom, unlike the forzados. Their owners could reclaim them; if they did not, the slaves remained in galley service.12
Galleys became increasingly obsolete in the eighteenth century, and, even before they were abolished in 1748, the slaves and forzados no longer principally worked as rowers. The galleys usually remained in port and their involuntary crews worked in the naval yards. After the galleys were abolished, it was a natural step for the government officials to assign forzados and slaves to the naval arsenals. There they worked at various tasks of maintenance in the naval yards; their most arduous task was to operate the pumps that kept water out of the dry docks. Convicts continued to labor in the naval arsenals until 1818, but the last figures for slaves working in them come from 1786.13
Forzados and slaves also labored in public works and at the mercury mines at Almadén and the silver mines of Guadalcanal. Almadén was a particularly harsh environment. Toxic fumes from the furnaces produced mercury poisoning, and the heavy labor of operating the pumps debilitated the workers and left them vulnerable to infectious diseases. Some of the convicts even asked to be transferred to the galleys to escape the mines. By the early eighteenth century, slaves, usually purchased at low prices, came to be twice as common as convicts in the labor force. Improved technology in the eighteenth century, however, reduced the hazards of working there. It therefore became possible to recruit free workers, who ultimately replaced the slaves and forzados at Almadén.14
To sum up this section, slavery by birth was a constant throughout slavery’s history. Self-sale, debt slavery, and penal slavery did produce slaves, but not consistently and not in great numbers. None of these methods produced sufficient numbers of new slaves to meet demand. The capture and later enslavement of people born free provided the greatest number of slaves.
From Free to Slave
Captivity in war or in raids was the principal avenue to slavery for freeborn people. Both Romans and Visigoths enslaved captives. In the early years of the rise of Islam, when Muḥammad and his first followers secured control of the Arabian peninsula, the prisoners of war they captured, other Arabs, were enslaved if they were not ransomed. When the Muslims expanded beyond Arabia, the situation changed. By the time the Muslims took Spain, the possibilities of enslavement through war had declined sharply. Islamic religious tradition held that Jews and Christians were “people of the book,” fellow seekers after truth whose holy books governed their religious actions. As dhimmī, protected aliens, they could not be enslaved outright, although during the wars of expansion the victors often violated this prohibition. Free Muslims could not be enslaved legally, but occasional violations of this rule followed quashed revolts. There was no mass freeing of slaves in newly conquered areas, even if the slaves later embraced Islam, and the mere fact of conversion to Islam was not sufficient to free a slave.
The practice of slavery
