The Spanish treasure fleet was an annual convoy used to transport goods between the Spanish Empire in the Americas and metropolitan Spain in Europe. Large trade galleons would carrying riches from the colonies would gather into a fleet in Havana before sailing eastward across the Atlantic to Spain. Because of the vast wealth aboard these ships, the treasure fleet was the holy grail of targets for pirates. Capturing just one ship could bring a pirate large sums of gold, and make them famous for life.

When Spanish settlers first arrived in the Caribbean, the colonies they set up were not completely self-sufficient. Many towns relied on regular imports of goods from Spain in order to survive, and even those capable of existing on their own still required trade to obtain items such as luxury goods, European books, and tools. Additionally, the mercantilist laws of Spain forbade its colonies from trading with any other nations, so these settlements could only export goods to other colonies or back home to Europe. This meant that the annual arrival of the treasure fleet was one of the most important events to the economy of the Spanish Empire.

Once a year, two fleets sailed from Spain carrying the goods required by the colonies. These two fleets would separate upon entering the Caribbean. One would head south, stopping at the towns along the northern coast of South America, before heading to Panama. The second would head west into the Gulf of Mexico. Both fleets traded with the Spanish colonies throughout the New World, exchanging goods from Europe for the products they generated. In the Caribbean, these products were usually agricultural products such as tobacco, sugar, and spices.

The primary destination of the southern fleet was Nombre de Dios, in Panama. Here it would pick up silver from the mines of Peru and Chile. After being mined, the silver metal was transported up the Pacific coast of South America to Panama. From there, it was carried by mule on the Spanish Silver Train to Nombre de Dios, where it awaited the arrival of the treasure fleet. After the privateer Francis Drake sacked the city in 1572, the flow of silver was redirected to the nearby town of Portobelo, which was easier to protect – and so the treasure fleet began to visited that city instead. This fleet would also visit Margarita to obtain the pearls which were harvested from the local oysters.

The second fleet would make its way to Veracruz in Mexico. At this city, it was loaded with the gold and silver from the Spanish holdings in the former Aztec Empire. It also sometimes took on cargoes of porcelain, carried across the Pacific from China and overland to the Gulf by mule.

After exchanging their goods for the wealth of the colonies, the two fleets would head to Havana, the largest port of the Spanish Empire. From March through August the galleons trickled into Havana Bay, where they remained under the protection of the large forts and the Spanish Armada. In September, once all the ships had arrived, they would set sail for Europe on the winds of the Gulf Stream, with the navy guarding them the whole way. The purpose of this rendezvous was to make it harder for pirates to seize any of the vessels – by sailing together, they could protect each other, and the armada had only one fleet to guard.

The treasure fleet was the richest target any pirate could hope to capture. One of the earliest to do so was Jean Fleury, a French privateer who captured several of the galleons carrying Mexican gold in 1522. This attack occurred before the royal decree requiring all the ships to gather in Havana before setting sail, and helped convince the Spaniards to fortify their towns and protect the fleet. In 1628, a squadron of sloops under command of the Dutch admiral and privateer Piet Hein surprised the fleet off Cuba, and seized sixteen vessels. Despite these successes, few managed to conduct a successful raid on the treasure fleet. The strong protection made it one of the most successful naval operations in history, and most later attacks required the involvement of regular naval forces in wartime.