The siege of Ostend was a three-year siege of the city of Ostend during the Eighty Years' War and the Anglo–Spanish War. A Spanish force under Archduke Albrecht besieged the fortress being held initially by a Dutch force which was reinforced by English troops under Francis Vere, who became the town's governor. It was said "the Spanish assailed the unassailable; the Dutch defended the indefensible." The commitment of both sides in the dispute over the only Dutch-ruled area in the province of Flanders made the campaign continue for longer than any other during the war. This resulted in one of the longest and bloodiest sieges in world history: more than 100,000 people were killed, wounded, or succumbed to disease during the siege.
Ostend was resupplied via the sea and, as a result, held out for three years. A garrison did a tour of duty before being replaced by fresh troops, normally 3,000 at a time keeping casualties and disease to a minimum. The siege included a number of assaults by the Spanish, including an unsuccessful assault by 10,000 Spanish infantry in January 1602 when governed by Vere. After suffering substantial losses, the Spanish replaced the Archduke with Ambrosio Spinola, and the siege settled down to one of attrition, with the strong points gradually being taken one at a time.
Ostend was eventually captured by the Spanish on 20 September 1604, and the city was completely destroyed; the overall strategy had changed since the siege had started. The loss of Ostend represented a significant strategic setback for the Dutch Republic and England, but the outcome of the siege also came at great cost to Spain. The three-year siege of Ostend, marked by heavy casualties and high costs, was further partially offset by the Dutch and English conquest of Sluis shortly before its conclusion, yielding limited long-term strategic value. In this regard, it has been described as a pyrrhic victory, as the financial burden contributed to Spain's bankruptcy in 1607, and led the subsequent Twelve Years' Truce.
Background
In 1568, during the reign of Philip II of Spain, the Netherlands, until then under the rule of the Spanish Empire, took up arms against the Spanish crown. The first phase of the war began with two unsuccessful invasions of the provinces by mercenary armies under Prince William the Silent of Orange (1568 and 1572) and foreign-based raids by the Geuzen or Sea Beggars, (irregular Dutch land and sea forces). By the end of 1573 the Beggars had captured the bulk of the provinces of Holland and Zeeland as well as converted the populace to Calvinism, and secured against Spanish attack. The other provinces joined in the revolt in 1576, and a general union was formed.
In 1579 the union was fatally weakened by the defection of the Roman Catholic Walloon provinces in the Union of Arras. By 1588 the Spanish, under Alexander Farnese, Duke of Parma, had reconquered the southern Low Countries leaving only Ostend as a major rebel enclave along the coast and stood poised for a death blow against the nascent Dutch Republic in the north. Spain's concurrent enterprises against England and France at this time, however, allowed the Republic to begin a highly successful counter-offensive under Maurice of Orange which lasted from 1590 to 1600, known as the Ten Glory Years.
In 1599 the Archduke Albert of Austria and Isabel Clara Eugenia, brother and sister of Philip III, ruled as joint sovereigns of the Netherlands through the will of the dying Philip II. By 1600 Maurice of Nassau was stadtholder and Johan van Oldenbarnevelt was Grand pensionary of the States General of the Netherlands.
In 1601, Spain, now under King Philip III with his favourite the Duke of Lerma, despite maintaining its hegemony in the world, was economically weakened with war and bankruptcy. Starting with the bankruptcy of the Royal Treasury in 1575; operations against the Ottomans in the Mediterranean, thirty years of war in Flanders against the rebel forces of the United Provinces and a war with England which had waged from 1585. Spain had also only just finished a costly and unsuccessful war with France. The wars were a great burden for the Spanish Empire and meant that financially Spain depended entirely on the treasure fleet brought from the colonies. Nevertheless, Philip pursued a highly aggressive set of policies, aiming to deliver a 'great victory' against both Holland and England. The situation of the United Provinces was similar; more than thirty years of war, and foreign trade blocked by Spain had caused a financial drain. The Dutch tried to relieve their precarious finances by commercially expanding into the East Indies with the birth of the Dutch East India Company (VOC). England was in the same position and was fighting now in Ireland. Like the Dutch they too had just set up their own East India Company.
In 1600 the Dutch and English Army under the command of Maurice of Nassau and Francis Vere respectively used Ostend as a base to invade Flanders, in an attempt to conquer the city of Dunkirk after their victory in the Battle of Nieuwpoort. This never happened however as disputes in the Dutch command meant that taking Spanish-occupied cities in the rest of the Netherlands took over priority as the opportunity arose. Maurice concurred and had his forces evacuated by sea leaving Ostend to be preoccupied by the Spanish.
Ostend
Founded five hundred years earlier, the city of Ostend (translated into English meaning East – End) in the mid-16th century was a fishing village of about 3,000 inhabitants. Ostend's strategic position in the province of West Flanders, along the North Sea and accessible to Dutch sea power, was fortified by the Dutch and English between 1583 and 1590, and turned into a major military port. In the view of the State of Flanders; Ostend in the hands of the Protestant Dutch and English was a huge thorn in their side. Ostend unlike other places in the Netherlands had never been taken by the Spanish and the garrison had even repelled an attack by Parma in 1583. In 1587, during preparations for the invasion of England by the Spanish Armada, Parma had rejected the idea of a conquest of Ostend by considering it a reckless enterprise after the capture of Sluis. The garrison had also made frequent incursions into the adjacent country. Ostend was the only possession of the Dutch Republic in Flanders and its capture was of strategic importance for the Spanish.
Defenses
The reason why Parma was so cautious to attack was not just for its defences, but also its place right near the sea. The old church and town faced the seas, but in 1583 the new town, further inland, was fortified with ramparts, counterscarps, and two broad ditches. The dunes were cut away, and the sea was allowed to fill the ditches and surround the town. A canal called the Geule had begun to form a new harbour on the east side; it was wide, deep, and navigable and served the maritime traffic to the city. To the south a framework of often flooded streams and wetlands would have made the area difficult to place heavy siege guns. Where the land rose slightly towards the dunes, on either side of the town; the besiegers would be able to approach with their parallels and batteries and as such were vulnerable points.
On the West side of Ostend another canal, the Old Haven, was more of a defensive moat which was barely navigable but could not be easily waded except for four hours at low tide. A ditch passed between the old and new towns, which were connected by bridges, and round the new town, parallel to the Geule on one side, and to the old harbour and Yperlet stream on the other. The Guele itself had ramparts and bulwarks on one side, and a counter scarp with ravelins on the other, while the water level for both canals could be adjusted from the lock located in the city.
In the old town, closer to the mouth of the old harbour, a fort called the Sandhill had been constructed. The old town was protected by strong palisades forming bastions with connecting curtains, and a succession of three small forts; the Schottenburgh (next to the Sand-hill), the Moses Table, and the Flamenburg all defending a cut from the town ditch into the Geule, at the eastern corner. On the eastern side of the town facing the Geule, the defences consisted of a range of bulwarks (or bastions) North Bulwark, East Bulwark or Pekell, Spanish Bulwark at the southeast angle, with an outwork called the Spanish Half-moon. To the South and West an extensive outwork, the Polder, which had formerly been a field from which the water had been pumped by means of windmills near the point where the Yperlet stream flowed into the old harbour. Flanking the Polder at both points were the South bulwark and the West bulwark, in front of each were two further outworks; the inner stronger Polder, South and West Bulwark's which then linked the Polder, South and West Ravelins. This then linked to the Polder, South and West square's; Ostend's most outer defensive works.
At the northwest angle, near the mouth of the fordable old harbour, the walls consisted of a strong ravelin in the counter scarp called the Porcepic, and a bastion in its rear known by the name of the Helmund. This was considered the most important area to defend as an attempt on the walls could be made on firm ground.
The north area was open to the sea, where Ostend could receive reinforcements and supplies during the high tide.
Forces
Armies during this period of warfare utilized pikes, arquebuses, swords, daggers, rudimentary (and unpredictable) explosives; early forms of hand grenades as well as artillery. As there were more wounded than deaths in battle, amputations were the common solution for treating wounds. At this time poor sanitation spread infections and fever, causing more deaths than combat itself.
The tercios, the regiments of the Spanish army, were regarded at the time as the elite of the military corps, and were key to Spain's European hegemony in the 16th century and the first half of the seventeenth century, and are seen by historians as a major development of early modern combined arms warfare. The quality of their organization and strict discipline made them efficient but certain circumstances such as long delays in pay sometimes escalated into violent mutinies. The tercios consisted of recruited soldiers of all domains of the Spanish Habsburg empire; Spaniards, Portuguese, Italians, Germans, Walloons, Swiss, Burgundians loyal to Spain, and dissident Catholic Irish, along with mercenaries from other countries. They were led by the Archduke Albrecht who was military commander of the Spanish forces in the Low Countries.
The defending forces of Ostend were the army of the United Provinces, reorganized by Maurice of Nassau who also played a part in the development of early modern warfare. The Dutch had large support from their Protestant ally England whose pike men and arquebusiers were clad in red cassocks (amongst the earliest English redcoats). The English, having distinguished themselves highly in battles such as Turnhout and Nieupoort where they had faced and beaten the Spanish tercios, were considered the veterans, and the elite of the army as a whole. They did have a reputation however as being thieves, pillaging friend and foe alike during and after battle. Other Protestant troops from Scotland, France, and Germany took their side amongst Maurice's army.
Siege
On 5 July 1601, the Archduke Albert opened the siege of Ostend with 12,000 men and 50 siege-guns in position; while the small garrison of under 2,000 was commanded by Governor Charles van der Noot. The States General held that the defence of this outlying post was a matter of vital importance. With this in mind they looked round for the ablest commander in their service. Sir Francis Vere, the hero of Nieuwpoort, was chosen not as governor, but as general of the army along with ample powers.
The Spanish besiegers soon rose to 20,000, a number which was one of the Archduke's preliminary objectives. As the Spanish cannonaded the city, some soldiers tried to wade the moat but this failed and a number drowned. The Count of Bucquoy, commanding forces east of Ostend, had been unable to do the same due over Geule, and began the construction of a dike from the sea up to the city; artillery was placed with which to fire at the boats coming and going from the North. These works were constantly interrupted by the rising sea, evolving under fire from the city and in addition the superiority of the Dutch and English at sea. In addition, the failure of the Spanish closing the north side of Ostend enabled it to receive reinforcements and supplies.
Vere first proceeded to England to obtain the approval of Queen Elizabeth, and to raise a body of recruits – these were subsequently raised in East Anglia while some were pressed into service in London. Vere's brother Horace was detached from Maurice's army with eight English companies to reinforce the Ostend garrison.
Arrival of Vere
On 9 July, Sir Francis landed with these troops on the sands opposite Ostend. Van der Noot met him at the water's edge, and delivered up the keys of Ostend. The garrison then consisted of thirty companies of Netherlanders in two regiments of 2,600 men to which Vere added his eight companies of 100 men each, which brought up the total to 3,500 men. Another 1,500 English troops under Edward Cecil arrived on 23 July to build up the garrison.
On 27 July English troops led by Edward Cecil made a sortie and gained a large segment of trenches from the Spanish whom they put to flight; pursuing them to the sand hills with support from the town's artillery. Casualties inflicted were heavy; around 600 including many prisoners. Amongst the killed was Don Diego Idiaquez, son of a former secretary of state to Philip II.