Spain's Philip II was in the Netherlands when his father abdicated in 1556. As we have seen, difficulties with rebellious subjects kept him there for three years. Within a decade of his return to Spain, the Dutch revolt had flared into the series of conflicts that became known as the Eighty Years' War. (fn)
(fn: The Eighty Years' War or Dutch War of Independence (1568–1648) led to the separation of territories in northwestern Europe formerly ruled by the Hapsburgs into the modern-day Netherlands, Belgium and Luxembourg. While Hapsburg rule in the southern provinces lasted until 1714, the northern regions became the United Provinces of the Netherlands (a.k.a. the Dutch Republic) after 1581. However, while the Dutch managed to oust the Habsburg armies from their heartland, the fighting continued on its frontiers. Dutch attacks on Spain and Portugal's overseas territories resulted in the establishment of their colonial empire.)
Events on the ground in the Netherlands seemed to be running Philip's way when his nephew Sebastian disappeared in northern Morocco during the disastrous Battle of Alcácer Quibir (1578). Sebastian had succeeded to the Portuguese throne as a three-year-old in 1557. He died without providing his kingdom with an heir to the throne. Sebastian's great-uncle Henry was the last surviving member of the House of Aziz and subsequently became king of Portugal.
However, Henry the Chaste was a Cardinal and seemed to have followed his vow of celibacy. Although he sought a release from his vows to take a bride and continue the Aviz dynasty Pope Gregory XIII prefered not to antagonise Philip.
When Henry died on his 68th birthday, without an obvious successor, Philip sent the Duke of Alba to claim the Portuguese throne by force in November 1580.
The Portuguese Cortes duly appointed him to the throne on one condition – Portugal and its overseas territories would retain their autonomy.
However, Philip's ascent to the throne gave him power over Portugal's commercial relations that he could use against his rebellious Dutch subjects.
While Portugal's limited maritime resources could handle the trade with the East Indies, Dutch ships carried the goods they brought back to northern Europe.
When Philip closed Portuguese ports to Dutch shipping, they had to look elsewhere for Oriental merchandise.
At least, that was the official position.
Philip's embargo on Dutch traders visiting Lisbon appears to have been honoured at least as much in the breach as in the observance for very sound reasons.
Dutch merchant vessels were by far the most economical option in the maritime carrying trade in the Atlantic.
Even in the middle of the 17th century, Dutch vessels carried the bulk of sugar exports from Brazil while Dutch interests were trying to evict the Portuguese from South America.