It has been argued that the history of the world would have been very different had Napoleon Bonaparte not underestimated the power and accuracy of British naval gunnery. Another who made the same error was a Brazilian sailor called João Cardozo dos Santos. In September 1827, while master of the slave vessel Henriqueta, dos Santos foolishly attempted to cross the bow of a British frigate, HMS Sybille, while being chased across the Bight of Benin. This brought dos Santos within range of Sybille’s long twelve-pounders, which flashed into life at the critical moment. ‘In an instant,’ Stephen Taylor writes in this compelling, superbly researched history, ‘Henriqueta’s rigging was shredded. She slowed, all the attributes that gave her advantage swept away, her sails in tatters, her beauty lost.’

Beauty, perhaps, but beauty of the most disturbing kind. By the time of her capture in 1827, the Henriqueta was among the most notorious of the slaving vessels in the mid-Atlantic. Owned by a slippery Portuguese trader, José de Cerqueira Lima, who lived in great splendour in the Brazilian city of Bahia (now known as Salvador), the vessel had been built to an innovative new design at Baltimore in the United States. ‘Baltimore clippers’, as the class was generally known, were renowned for speed. Slender with ‘arrowy hulls and raking masts’, they could cleave through the water at fourteen knots, covering as many as two hundred nautical miles a day. Should the winds fail, as they often did in the equatorial regions, the Henriqueta was fitted with sweeps that provided an alternative (or additional) mode of propulsion.

Speed had long been a consideration for slavers. Bluntly put, a faster voyage would, theoretically, deliver a greater number of living Africans to the American markets. The reality was not so simple, however. Slavers responded to improvements in mortality rates by cramming more and more victims into the holds of