Siege of Ostend

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Siege of Ostend
Layout;  Center of Ostend in 1601
Layout; Center of Ostend in 1601
date July 5, 1601 to September 20, 1604
place East End
output Spanish victory
Parties to the conflict

Republic of the Seven United ProvincesRepublic of the Seven United Provinces United Netherlands

Spain 1506Spain Spain


Daniël de Hertaing
Francis Vere

Archduke Albrecht VII of Austria
Ambrosio Spinola

Troop strength
about 7,000 men about 12,000 men



The siege of Ostend found during as Eighty Years' War marked Dutch instead struggle for independence. Spanish troops began the siege of the city defended by the Dutch on July 5, 1601 . On September 20, 1604 , the Dutch garrison capitulated. It is one of the most costly sieges of the early modern period .


In the Hapsburg- ruled Spanish Netherlands , the tough Spanish policy, especially against the mostly Calvinist Dutch, led to armed conflicts since 1568. The south of the Spanish Netherlands, which is predominantly inhabited by Catholic Walloons , founded the Arras Union, loyal to Spain, in January 1579 . This union included the counties of Artois , Hainaut and the southern part of Flanders . In response to this, the insurgent Union of Utrecht was formed in the same month , which not only covers Holland , Friesland , Zeeland , Geldern , Overijssel , Drente and Groningen ("The Seven Provinces"), but also the northern and western parts of Flanders Part of Brabant included. The Union of Utrecht renounced Spanish rule in 1581.

The Spanish-Habsburg troops under the Duke of Parma went on the offensive against the rebellious Dutch and Flemings in 1581 and pushed them back from Flanders and Brabant by 1590. Groningen, Drenthe, a large part of Overijssel and the eastern part of Geldern were also conquered by the Spanish. On the North Sea coast of Flanders, however, Ostend was able to maintain itself as a Dutch exclave . Several setbacks for the Spanish Habsburgs followed. Under Moritz of Orange , the Dutch managed to recapture six cities by 1592, and in December of that year the Duke of Parma died of a serious injury. On June 30, 1600, Dutch troops landed on the Flemish coast and on July 2, at Nieuwpoort, they won a victory over the Spaniards, which they could not exploit. The Spaniards felt compelled to act and decided to attack Ostend.

Course of the siege

Starting position

On July 5, 1601, a Spanish army with a strength of around 12,000 men under the command of Archduke Albrecht VII of Austria appeared in front of Ostend. It consisted not only of Spaniards, but also of Burgundians, Germans, Italians and Walloons. The port city was almost completely surrounded by water, while there were various dunes in the surrounding area . The residents of the city had spent several years building a double ring of bastions and ramparts to protect the city. These fortifications consisted of heavily sandy earth, were provided with palisades and surrounded by wide moats. The Dutch had built numerous forward fortifications in the swampy surroundings of the city. The city was defended by a garrison of about 7,000 men. Ostend was in constant contact by sea with the core areas of the uprising, Zeeland and Holland. From there ammunition, food, weapons and personnel reinforcements were permanently embarked.

The sand hill bastion

During the first months of the siege, the Spaniards were busy conquering the area around the city in arduous battles until they could launch attacks on the walls of Ostend. For this purpose, the Spaniards posted heavy artillery on a dune west of the city. From there, they shot at the so-called sand hill bastion in the northwest of Ostend. The high bastion, made of sandy earth, absorbed several thousand cannon balls without being seriously damaged. The battles for the sand hill bastion were extremely costly for the Spaniards. During the breaks in the fighting, some of the besieged came out of town and cut the flesh from the bones of the corpses lying around, as human fat was believed to be an effective ointment. On the night of January 7th to 8th, 1602, the Spanish troops launched an assault on the sand hill bastion via the beach north of the city, but it failed. This attack alone cost the lives of around 2,000 people on the Spanish side. After that, the Spaniards did not undertake any further assault on Ostend until 1603, but limited themselves to fortifying the dune west of the city and taking the city under gunfire from there. During this phase of the siege, more and more onlookers came to Ostend. The constructions of a fortress engineer sent by the Pope to support the Spaniards turned out to be useless.

The fighting under Spinola

In the late summer of 1603, the Spaniards Ambrosio Spinola and new troops arrived off Ostend to strengthen them . He had hardly any military experience, but had acquired certain skills by studying relevant books. He avoided a large-scale assault and instead made sure that his troops slowly worked their way through the construction of field fortifications to the northwestern part of Ostend. This approach was also costly, but it turned out to be successful for the Spaniards. On April 4, 1604, in a surprise attack, the Spanish succeeded in taking several fortifications near the sand hill bastion. Shortly afterwards the defenders of Ostend withdrew to the inner defensive ring. By the summer the besieged had to give up this ring too. They withdrew to a makeshift citadel in the northeast of the city, which had four bastions.

The end of the siege

The fall of Ostend was hastened by the forces of nature. In August 1604 storms broke out, which made it difficult for Dutch ships to continue to supply Ostend. A Dutch army under Moritz von Oranien went to Sluis to move the Spanish besiegers of Ostend to a field battle. But that did not happen, which is why Moritz decided to siege Sluis. A Spanish relief army was repulsed and the city was taken by Moritz on August 17th. However, this event did not change the fate of Ostend. On August 22nd, a strong storm and high tidal waves carried away a considerable part of the fortifications still held by the besieged. A further defense of the city had thus become hopeless, so that the governor of Ostend, Daniël de Hertaing , opened negotiations with the Spanish. The governor had numerous Dutch soldiers, Calvinist pastors and Spanish deserters brought out of the city by sea and during the surrender negotiations on September 20, 1604, he received permission from the Spanish to withdraw with his remaining garrison. The withdrawal on September 22nd was uneventful, and on the same day Spanish troops occupied Ostend.


The siege of Ostend is one of the most costly in the early modern period. The constantly increasing Spanish troops suffered around 40,000 deaths, both from a fatal wound and from illness. The losses of the besieged are difficult to estimate, as Dutch ships made about 3,000 trips from Holland and Zeeland to Ostend, taking in wounded and sick people, who in many cases only survived a few days at the most. It can be assumed that there were almost as many fatalities as on the Spanish side. The political consequences of the conquest of Ostend by the Spaniards appear much less significant in comparison. The Dutch permanently lost their last base on the Flemish coast. The fighting over Ostend had weakened both sides to such an extent that, despite further military clashes, a twelve-year armistice was negotiated as early as 1609. The loss-making Dutch struggle for independence, which was primarily a fortress war, only finally ended with the Peace of Westphalia in 1648.

See also

List of sieges


  • JeremyBlack: European Warfare, 1494-1660 . Routledge, London 2002; ISBN 0-415-27532-6
  • Christopher Duffy: Siege Warfare: The Fortress in the Early Modern World, 1494-1660 . 2nd Edition. Routledge, London 1996; ISBN 0-415-14649-6

Individual evidence

  1. ^ Siege of Ostend Journal
  2. ^ City of Ostend: 1604 (Dutch), accessed on September 21, 2010