The Eighty Years' War or Dutch Revolt (Dutch: Nederlandse Opstand) (c.1566/1568–1648) was an armed conflict in the Habsburg Netherlands between disparate groups of rebels and the Spanish government. The causes of the war included the Reformation, centralisation, taxation, and the rights and privileges of the nobility and cities.

After the initial stages, Philip II of Spain, the sovereign of the Netherlands, deployed his armies and regained control over most of the rebel-held territories. However, widespread mutinies in the Spanish army caused a general uprising. Under the leadership of the exiled William the Silent, the Catholic and Protestant-dominated provinces sought to establish religious peace while jointly opposing the king's regime with the Pacification of Ghent, but the general rebellion failed to sustain itself.

Despite Governor of Spanish Netherlands and General for Spain, the Duke of Parma's steady military and diplomatic successes, the Union of Utrecht continued their resistance, proclaiming their independence through the 1581 Act of Abjuration, and establishing the Protestant-dominated Dutch Republic in 1588. In the Ten Years thereafter, the Republic (whose heartland was no longer threatened) made conquests in the north and east and received diplomatic recognition from France and England in 1596. The Dutch colonial empire emerged, which began with Dutch attacks on Portugal's overseas territories.

Facing a stalemate, the two sides agreed to a Twelve Years' Truce in 1609; when it expired in 1621, fighting resumed as part of the broader Thirty Years' War. An end was reached in 1648 with the Peace of Münster (a treaty part of the Peace of Westphalia), when Spain retained Southern Netherlands and recognised the Dutch Republic as an independent country.