London's advantage in the slave trade was everything but the weather

London organised slaving voyages on the strength of being the commercial capital of the Atlantic world. It was the largest city in Europe, and a merchant fitting out for Africa could buy there the whole range of goods the coast wanted, Indian textiles, iron bars, guns and brass, together with marine insurance, bills of exchange and credit on terms no rival could match. The one disadvantage was physical. Ships leaving the Thames often lost several weeks working down the English Channel against the prevailing westerlies, a delay that Liverpool and Bristol were spared by geography. The financial advantages outweighed it. London vessels distributed captives across a wider range of New World territories than those of any other port, selling into British, Spanish, French and Dutch colonies as licences and wars permitted, and the city held its place as a primary international carrier through the eighteenth century. The slave trade ran on credit, and London was where the credit lived.

The Treaty of Ryswick, concluded in 1697, obliged Spain to cede a third of Hispaniola to France. The ceded territory took the name Saint-Domingue. Sugar was already being made there, and the arrival of enslaved labour in quantity was about to change how it was produced. Through the eighteenth century the traffic in captives climbed to its peak before falling away, in the language of the day, for want of supply. Ships were built larger to carry more people. Captives lay chained in pairs in holds that the trade itself called floating tombs, and the crossing to Saint-Domingue took between forty and ninety days on short rations. Most African regions were represented in the colony, and among the three largest groupings the Fon of Dahomey, combined with the Yoruba of what is now Nigeria, supplied the framework on which the transplanted religious practice of the island was built.

Barbados began as a tobacco colony worked largely by indentured Europeans, and it did badly, undersold by Virginia. In the 1640s the planters changed crop. Sugarcane needs a mill, a boiling house, fuel and a large permanent workforce, so changing the crop changed everything else: land consolidated into estates, smallholders were bought out, and the workforce became African and enslaved. Dutch and Sephardic merchants trading out of Brazil and Amsterdam supplied the technical knowledge, the credit and the shipping. Within a generation Barbados was the most valuable ground in the English empire, and every other island copied it. Saint-Domingue copied it later than most and then outgrew all of them, producing more sugar by the 1780s than Barbados and Jamaica together. What the Barbadian model fixed was a ratio, a small planter class governing a large enslaved majority that it could neither replace nor reproduce. That ratio is the precondition for everything that happens in Saint-Domingue in 1791.

In February 1644 a group of enslaved Africans in New Amsterdam petitioned the Dutch authorities for their freedom. They had served the Dutch West India Company for eighteen years, they said, and they were burdened with so many children that they could no longer support their families while they stayed in the company's service. The Council of New Netherland granted what historians call half freedom to the named petitioners and their wives. In exchange each man owed the company a yearly payment of wheat and a hog valued at twenty guilders. The council also ruled that their children, those already born and those yet to be born, would serve the company as slaves. The petitioners carried names recording where they had passed through, Paulo Angola, Simon Congo, Anthony Portugis, Jan Fort Orange. They spoke some Dutch and some Portuguese and had stood on two other continents. Their wives appear in the ruling without names.