How slavery became part of the economy

A voyage across the Atlantic was long, and a ship carrying goods one way and returning empty did not pay for itself well. The system established by the 18th century solved exactly this problem: there was cargo on every leg of the journey.

European ports shipped textiles, metal, weapons, and alcohol, exchanging them on the West African coast for people captured inland. The hold crossing the ocean was filled with people. Back to Europe came sugar, tobacco, and later cotton, grown by those brought over on earlier voyages.

Each leg was an ordinary business transaction with ordinary bookkeeping. That is what made the slave trade part of the economy, rather than its dark corner: it needed no separate rules, the usual ones were enough.

A service industry grew up around these voyages. You could profit without ever stepping aboard - and that is how most participants profited.

The clearest detail of the mechanism is insurance. A person's death in the hold was recorded as lost cargo. In 1781, the crew of the British ship Zong threw more than a hundred people overboard, and the owners claimed payment from insurers; 2 years later, a court heard the case as a dispute over cargo. The publicity became one of the arguments used by British abolitionists.

Losses were factored in from the start. According to estimates from the database of Atlantic voyages, about 12.5 million people were put aboard ships over the entire period, and about 10.7 million reached the Americas. The difference was people who died en route, listed in the accounts alongside spoiled sugar.

Responsibility dissolved in the process. The shipowner was responsible for the voyage, the insurer for risk, the banker for the bill, the manufacturer for raw materials. No one held the whole picture, and each person's piece looked like normal work. Historians still debate how much this profit financed the Industrial Revolution: their estimates vary widely.

If you expected a story about individual villains, the mechanism is more mundane and more frightening. The slave trade did not have to be specially built into the economy - it used the same tools used to transport textiles and grain, and abolishing it meant dismantling an entire industry with suppliers, creditors, and customers.