Saint-Domingue was the largest slave market in the Caribbean

For most of its existence Saint-Domingue was the leading point of disembarkation for enslaved Africans anywhere in the Caribbean, and it held that place until the revolution destroyed the plantation regime. More than 770,000 people were landed there. They came chiefly from Senegambia, the Bight of Benin and West Central Africa, the regions where French traders were strongest. Every major French Atlantic port, Nantes, Bordeaux, La Rochelle and Le Havre, treated the colony as its best market in the Americas through the eighteenth century, and the returns paid for town houses that still stand in those cities. The output justified the traffic in the eyes of the men running it: sugar, coffee and indigo in quantities no other colony matched. The same arithmetic produced the revolution. A territory that must import people on that scale in order to function has a population with no reason to defend it, and in 1791 it stopped functioning.

In the region around the Gulf of Benin, each ethnic group, village, family and lineage kept its own vodun, guardian deities tied to ancestors. Relations between these groups were marked by rivalry and frequent war, and religion moved with the fighting. At the opening of the eighteenth century the royal family of Abomey, extending its power, set out to centralise worship. It appropriated deities belonging to its enemies, among them Yoruba ones, suppressed some spirits and imposed others across the whole kingdom, so that these became public vodun. Priests who had until then worked independently of rulers were turned into dignitaries of the court. One imposed figure was Agassou, founding ancestor of the royal line at Abomey, held by tradition to be the child of a woman and a panther. Families went on honouring their own vodun regardless. Both habits, the state cult and the household one, crossed the Atlantic in the slave ships.

Between 1677 and 1682 an investigation at the court of Louis XIV drew in close to four hundred suspects. At its centre was a circle of noblewomen who commissioned love magic from a sorceress in Paris. Investigators then turned up something else. The same sorceress was said to have sold deadly poisons made from toads to heirs impatient for their inheritances, and to have had charms consecrated by rogue priests. The French script of the moment held that women used potions to make men love them, an inversion of order that frightened the powerful. The affair produced a royal edict in 1682 that criminalised pretended magic, punished superstitious use of sacred objects and prayers, and tightened the sale of arsenic and mercury sublimate. Its effect in France was to cut accusations of sorcery by renaming the accused as false sorcerers or poisoners. Forty two years later that edict was extended to the French islands of the Caribbean.

In 1741 the Conde das Galveas, viceroy of Brazil, sent the king a broadly positive report that ended with a warning about great illnesses sweeping Salvador, fluxes and people bleeding from the mouth. By the autumn of 1743 his tone had changed completely. More than five thousand people had sickened and died in recent years and the colony was in a terrible state. Jesuits at the Engenho de Santa Anna had already reported in the early 1730s that they could not cope with the number of sick around them. Galveas never wrote that these deaths were poisonings. In the same year as the alarming report he set in motion an ordinance on poison, which made administering it worth investigating even where nobody died, and required anyone selling poison to register with the state. Over the following decades denunciations to the Inquisition of causing or of treating such illnesses climbed rapidly.