From 1566 to 1790 the Spanish treasure fleet ran the first permanent transatlantic trade route, a convoy system designed by admirals Pedro Menendez de Aviles and Bernardino de Mendoza after French privateers sacked Havana. Every year two fleets left Seville under the monopoly of the Casa de Contratacion: the New Spain fleet to Veracruz for Mexican silver, cochineal, and Asian goods hauled by mule from Acapulco, and the Tierra Firme fleet to Cartagena and Portobelo for Potosi silver carried across the Isthmus of Panama. Both were required to rendezvous in Havana before crossing home.

The episode dismantles the pirate myth: in two and a half centuries remarkably few ships were lost to enemy action, and the real killers were Caribbean hurricanes in 1622, 1715, 1733, and 1750, made worse by a rigid schedule that forced fleets to sail into storm ...