The Anglo–Spanish War of 1585–1604 is an intermittent conflict between the kingdoms of Spain and England, which is never formally declared.

The war is punctuated by widely separated battles, and begins with England's unsuccessful military expedition in 1585 to the Netherlands under the command of the Earl of Leicester in support of the resistance of the Estates General to Habsburg rule.The English enjoy victories at Cádiz in 1587, and over the Spanish Armada in 1588, but lose the initiative upon the repulse of the English Armada in 1589 before La Coruña and Lisbon.

Two further Spanish armadas are sent but were frustrated in their objectives owing to adverse weather.In the decade following the defeat of the Armada, Spain strengthens its navy and is thereafter very successful in defending its transport of precious metals from the Americas.

England is on the losing end of most of the subsequent battles, but the war becomes deadlocked around the turn of the century during campaigns in Brittany and Ireland.

The war is brought to an end with the Treaty of London, negotiated in 1604 between representatives of Philip III and the new Scottish king of England, James I. Spain and England agree to cease their military interventions in Ireland and the Spanish Netherlands, respectively, and the English renounce high seas piracy.

Both parties have achieved some of their aims, but each of their treasuries has almost been exhausted in the process.