Siege of Sluis (1587)
Part of theEighty Years' War and theAnglo-Spanish War (1585–1604)
EngravingSiege of Sluis of 1587 byFrans Hogenberg. CollectionRijksmuseum Amsterdam.
Date 12 June – 4 August 1587 Location Sluis,Zeeland,Low Countries (present-day theNetherlands) 51°21′N3°30′E / 51.350°N 3.500°E /51.350; 3.500 Result Spanish victory[1][2]
Belligerents
States-General  England	Spain
Commanders and leaders
Robert Dudley Roger Williams	Alexander Farnese
Casualties and losses
700 killed and 400 wounded[3]	92 killed and 243 wounded[3]

Thesiege of Sluis of 1587 took place between 12 June and 4 August 1587, as part of theEighty Years' War and theAnglo-Spanish War (1585–1604).^[1][2] Its capture by the Spanish formed a significant advance towards theEnterprise of England.

June 1587 saw DonAlexander Farnese, Duke of Parma(Spanish: Alejandro Farnesio),Governor-General of the Spanish Netherlands, andcommander-in-chief of theArmy of Flanders, set his sights on the two remaining rebel ports in Flanders, Ostend andSluis. The latter had once been a strategic deep-water port, and was still (despite silting) a key to the inland waterways of the Flanders coast, and thus to any potential invasion of Britain.^[4] After an initial sortie against Ostend, Parma investedSluis on 12 June 1587, but not in time to prevent a body of four companies of English foot-soldiers reaching the town from Ostend under the command of SirRoger Williams.^[5] On 24 June, the bombardment of the town began.

A relief effort was organised by a fleet of English and Dutch troops under SirRobert Dudley, Earl of Leicester,Governor-General of the United Provinces.^[2][6][7] Leicester landed a force of 4000 foot, 400 horse at Ostend, to cut Parma’s communications, but called his men back to the fleet before coming to grips with any Spaniards; while a sea-borne attempt to force the channel and relieve the town was similarly aborted:Garrett Mattingly concluded that “The chief effect of this fortnight of imbecile manoeuvres was on the morale of the beleaguered garrison”.^[8] On 4 August, after of 13 days of constant fighting around the walls, the garrison surrendered with full honours of war.^[9]

The loss of the English-held port of Sluis revealed the inability of Leicester to assert his authority over the Dutch allies, who failed to cooperate successfully in relieving the town,^[10] and led to recriminations between thegovernor-general and theStates of Holland.^[6][11]

In the following months, the Earl of Leicester launched a series of unsuccessful attacks against the Spaniards.^[12] In September 1587, Leicester attempted to captureLeiden, but failed,^[12] and his plans to captureEnkhuizen andHoorn, two important ports ofWest Friesland, also failed.^[13] Notable English soldiers under Leicester's command were SirThomas Baskerville and SirFrancis Vere.^[13] On 16 December 1587, Leicester returned toEngland,^[13] where the privy council tried in vain to hold him to account for his failures, protected as he was by the favour of the Queen.^[14]

By contrast, Parma had gained a strategic prize that enabled him to move barges by inland waterways from the Scheldt to Dunkirk, preparatory to the coming of theSpanish Armada.^[15]

• Battle of Zutphen
• Siege of Bergen-op-Zoom (1588)
• Dutch Revolt
• List of governors of the Spanish Netherlands

• Martin, Colin./Parker, Geoffrey.The Spanish Armada: Revised Edition. Published 1989 by Penguin Books.ISBN 1-901341-14-3
• C. Duffy.Siege Warfare: The Fortress in the Early Modern World 1494–1660. Volumen 1. London.ISBN 0-7100-8871-X
• Tracy, James.The Founding of the Dutch Republic: War, Finance, and Politics in Holland 1572–1588. Oxford University Press. First published 2008.
• Wilson, Derek (1981).Sweet Robin: A Biography of Robert Dudley Earl of Leicester 1533–1588. Hamish HamiltonISBN 0-241-10149-2
• Van Nimwegen, Olaf.The Dutch Army and the Military Revolutions 1588–1688. First published 2010. The Boydell Press, Woodbridge.ISBN 978-1-84383-575-2
• Hammer, P.E.J. (1999).The Polarisation of Elizabethan Politics: The Political Career of Robert Devereux, 2nd Earl of Essex, 1585–1597. Cambridge University Press. Great Britain.ISBN 0-521-01941-9.

• L van der Essen, Alexandre Farnese Vol 3 (Brussels 1937)

• The Eighty Years War (1568–1648)
• The Founding of the Dutch Republic: War, Finance, and Politics in Holland 1572–1588

• Battles of the Eighty Years' War
• Sieges involving Spain
• Sieges involving England
• 1587 in Europe
• Conflicts in 1587
• 16th-century military history of the Kingdom of England
• History of Zeeland
• Sluis
• Eighty Years' War (1566–1609)

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