The Anglo-Spanish War, which had been threatening for twenty or more years, finally became an official, open, conflict in 1585. The decisive hostile move was the arrest of all the English merchant ships in Spanish ports in May of that year – a reprise on a larger scale of the duke of Alba's action in the Netherlands in 1568. But low-key hostil¬ities had continued all through the time since Hawkins’ defeat at San Juan de Ulloa, and since Drake's raid on the Isthmus of Panama. A contingent of English soldiers had already been fighting on the Dutch side in their rebellion against Spain for some time. The fighting in the war would clearly be concentrated in Europe, but the Caribbean – in the widest geographical sense – was clearly going to be involved, in part because it was likely to be a useful source of treasure with which to finance the English side of the war, but also because threats to Spanish power there could well provoke Spain to invest power and resources in what was essentially a sideshow, separate from the main theatre of the war in Europe.

Inevitably, however, given their joint history since Hawkins’ first voyage in 1562, the activities of both sides during the war in the Americas partook as much of privateering, even piracy, as they did of formal warfare; indeed, any ‘formal’ warfare in the Caribbean looked very much like privateering. The Caribbean conflict had begun (rather like the later wars with France) with English aggression into territory claimed by Spain in North America, as well as the continuing privateering in the West Indies; but attempts to trade had also continued. In 1583 William Hawkins, John's brother, in a voyage which is very badly recorded, had raided the pearl fishery of La Margarita off the eastern Spanish Main, but he had combined this with selling goods to the Spaniards ashore; he then traded at Porto Rico. He had a cargo of slaves, which he offered to the Porto Ricans, and it may be he had then topped it all off with the capture and looting of a ship carrying treasure.