Dutch–Portuguese War in the context of "Thirty Years War"

The Republic of the Seven United Netherlands (Dutch: Republiek der Zeven Verenigde Nederlanden), also known as the United Provinces (of the Netherlands), and referred to in historiography as the Dutch Republic, was a confederation and great power that existed from 1588 until the Batavian Revolution in 1795. It was a predecessor state of the present-day Netherlands and the first independent Dutch nation state. The republic was established after seven Dutch provinces in the Spanish Netherlands revolted against Spanish rule, forming a mutual alliance against Spain in 1579 (the Union of Utrecht) and declaring their independence in 1581 (the Act of Abjuration), after which they confederated in 1588 (the Instruction of 12 April 1588) after the States General could not agree on a new monarch. The seven provinces it comprised were Groningen (present-day Groningen), Frisia (present-day Friesland), Overijssel (present-day Overijssel), Guelders (present-day Gelderland), Utrecht (present-day Utrecht), Holland (present-day North Holland and South Holland), and Zeeland (present-day Zeeland).

Although the state was small and had only around 1.5 million inhabitants, it controlled a worldwide network of seafaring trade routes. Through its trading companies, the Dutch East India Company (VOC) and the Dutch West India Company (GWC), it established a Dutch colonial empire. The income from this trade allowed the Dutch Republic to compete militarily against much larger countries. Major conflicts were fought in the Eighty Years' War against Spain (from the foundation of the Dutch Republic until 1648), the Dutch–Portuguese War (1598–1663), four Anglo-Dutch Wars (1652–1654, 1665–1667, 1672–1674, and 1780–1784), the Franco-Dutch War (1672–1678), War of the Grand Alliance (1688–1697), the War of the Spanish Succession (1702–1713), the War of Austrian Succession (1744–1748), and the War of the First Coalition (1792–1795) against the Kingdom of France.

The Thirty Years' War, fought primarily in Central Europe between 1618 and 1648, was one of the most destructive conflicts in human history. An estimated 4.5 to 8 million soldiers and civilians died from the effects of battle, famine, or disease, with parts of Germany reporting population declines of over 50%. Related conflicts include the Eighty Years' War, the War of the Mantuan Succession, the Franco-Spanish War, the Torstenson War, the Dutch–Portuguese War, and the Portuguese Restoration War.

Its causes derived from religious conflict within the Holy Roman Empire, sparked by the 16th-century Reformation. The 1555 Peace of Augsburg attempted to resolve this by dividing the Empire into Catholic and Lutheran states, but was later destabilised by the expansion of Protestantism beyond these boundaries. Combined with disagreements over the limits of imperial authority, religion was thus an important factor in starting the war. However, its scope and extent was largely the consequence of external drivers such as the French–Habsburg rivalry and the Dutch Revolt.

The Restoration War (Portuguese: Guerra da Restauração) between Portugal and Spain began with the Portuguese revolution of 1640 and ended with the Treaty of Lisbon in 1668, bringing a formal end to the Iberian Union.The period from 1640 to 1668 was marked by periodic skirmishes between Portugal and Spain, as well as short episodes of more serious warfare, much of it occasioned by Spanish and Portuguese entanglements with non-Iberian powers. Spain was involved in the Thirty Years' War until 1648 and the Franco-Spanish War until 1659, while Portugal was involved in the Dutch–Portuguese War until 1663.

In the 17th century and afterwards, this period of sporadic conflict was simply known, in Portugal and elsewhere, as the Acclamation War. The war established the House of Braganza as Portugal's new ruling dynasty, replacing the House of Habsburg, which had been united with the Portuguese crown since the 1580 succession crisis.

The Dutch States Navy (Dutch: Staatse vloot, lit. 'States fleet') was the navy of the Dutch Republic from 1588 to 1795. Coming into existence during the Eighty Years' War, the States Navy played a major role in expanding and protecting the Dutch colonial empire, in addition to participating in numerous conflicts with rival European powers. The States Navy consisted of five admiralties, which were respectively based in Amsterdam, Friesland, the Noorderkwartier, Rotterdam and Zeeland. This organisational structure contributed to the decentralised nature of the States Navy, which heavily relied upon privateers and armed merchantmen in times of war.

In addition to the Eighty Years' War, the States Navy also participated in the Anglo-Dutch Wars, the Dutch–Portuguese War, the Northern Wars, the Franco-Dutch War and various conflicts of the French–Habsburg rivalry. It also played a major role in protecting Dutch overseas trade, including Dutch involvement in the triangular trade and the Atlantic slave trade. As a result of the War of the First Coalition, the Dutch Republic ceased to exist in 1795, being succeeded by the Batavian Republic; the States Navy was correspondingly transformed into the Batavian Navy. The current navy of the Netherlands, the Royal Netherlands Navy, is the modern successor of the States Navy and inherited many of its traditions.

A succession crisis emerged in Portugal in 1580 as a result of the disappearance of the young King Sebastian in the Battle of Alcácer Quibir in 1578 and the death of his great-uncle King Henry in 1580. As Sebastian and Henry died childless, a dynastic crisis unfolded, marked by internal conflicts and external contenders vying for the Portuguese throne. Ultimately, King Philip II of Spain succeeded, uniting the Portuguese and Spanish Crowns in the Iberian Union. This personal union endured for 60 years, during which the Portuguese Empire faced decline and global challenges, notably the Dutch–Portuguese War.