Fort de Mardyck

In the late 16th and early 17th century the Spanish-held port of Dunkirk was a base for privateers that preyed on Dutch shipping in the English Channel. The Dutch often blockaded Dunkirk with a small fleet in an attempt to prevent the privateers from putting to sea. The entrance to the port of Dunkirk was via a narrow deep water channel, called the Fosse de Mardyck, between the coast and a sandbank, so the Dutch ships could wait at the mouth of this channel to catch the Dunkirkers.

At the end of the twelve-year truce (1609-1621) between Spain and the Dutch provinces, the Dunkirkers prepared for war again. Anticipating the resumption of the Dutch blockade, an engineer called Jean Gamel proposed an unusual solution to protect the entrance to the port: an offshore battery made of wood. The new battery was built in 1622, supported by wooden piles driven deep into the sand. It was constructed on the low tide mark so as to be in range of any ships approaching the Fosse de Mardyck. Officially called the Batterie de Notre-Dame de Montaigu, the fort quickly became known simply as the "Wooden Fort" - "Fort de Bois" in French or the "Houte Wambus" in Flemish.

The wooden fort was initially designed to be a self-contained work with no landward fortifications. There were two two-storey buildings on the sides that contained stores and accommodation for the small garrison. The fort was linked to the mainland by a long wooden jetty, which was secured by a drawbridge just behind the fort and a gate halfway along. The focus was on the curved battery of guns that faced out to sea, because the Dunkirkers did not see any real danger of the fort being attacked from the land.

The wooden fort proved its value on several occasions by supporting Spanish and Dunkirker ships against the Dutch blockading fleet. It forced the Dutch ships to keep their distance from the Fosse de Mardyck, allowing the Dunkirkers to slip in and out of the port. However an event that occurred in 1629 demonstrated that enemy ships were not the only threat to the wooden fort. In that year the Dutch, frustrated with their ineffective blockade, sent a fleet to attack Dunkirk. The Dutch ships engaged the wooden fort and some privateers, but they received heavy damage and had to withdraw. During this attack some marines were landed on the coast not far from the wooden fort. In response the governor of Dunkirk sent a force of cavalry, which quickly sent the Dutch marines scurrying back to their boats. It may have been the raid of 1629 that prompted the construction of the first landward fortifications to protect the wooden fort.

This landward fortification was a small square fort with four bastions, revetted in brick and surrounded by a flooded ditch. A continuous false bray ran around the fort at the foot of the wall, from which musketeers could fire across the ditch. Inside was a small chapel, barrack buildings and stores. After the construction of fortifications on the land, the fort became known as the Fort de Mardyck or Fort van Mardijk, named after a nearby village.

However, the square fort was rather small and it was later supplemented by the addition of an outer fort with three bastions, also surrounded by a flooded ditch. This outer fort had lower walls, so it became known as the lower fort, and the original square fort became known as the upper fort. With the construction of the lower fort the Fort de Mardyck was capable of holding a garrison of several thousand men. It had ceased to be merely a means of landward protection for the wooden fort and it was now an outlying fort of Dunkirk, protecting it against an attack from the west.

This turned out to be just as well since the French made several advances into the Spanish Netherlands in the 1640s. In 1644 they captured Gravelines, about 10 miles (17km) to the west of Dunkirk. In 1645 the French laid siege to the Fort de Mardyck and captured it. When it became obvious that they would have to surrender, the garrison set fire to the wooden fort to prevent the French from using it to attack ships entering and leaving Dunkirk. So French troops occupied the Fort de Mardyck, but they did not rebuild the wooden fort. Later the same year the governor of Dunkirk heard that the French garrison was weakened by disputes between commanders, so he sent a force to make a surprise attack on the fort. The attack was successful and the Spanish recaptured the Fort de Mardyck. This success was short lived because the French returned in 1646 and took the Fort de Mardyck and Dunkirk itself.

When the French first took the fort in 1645 they started to improve the lower fort. This work was incomplete when the Spanish retook it by surprise, but it was resumed after the second French capture in 1646. The improvements consisted of enlarging the bastions and creating two new half-bastions by extending the lower fort to the north, so that it fully encompassed the three landward sides of the upper fort. This extension meant that the lower fort offered greater protection to the upper fort. The two original north walls were left in place inside the enlarged fort so that they could be used in case an enemy broke into one of the extended areas. They also added new demi-lunes, a covered way and a second ditch to the lower fort.

The Spanish had not given up on Dunkirk for good and they returned in 1652 and retook Dunkirk and the Fort de Mardyck from the French. The wooden fort was rebuilt, but to a slightly simpler design. There was no need for such large barracks and stores in the wooden fort now that there was a large fort with all those facilities on the land. Instead, supplies and ammunition could be moved from the main fort to the wooden fort as needed. The Fort de Mardyck was besieged and captured for the final time in 1658 by an Anglo-French force, which went on to take Dunkirk again. The difference this time was that Dunkirk and the Fort de Mardyck were now occupied by England, not by France.

The English occupation of Dunkirk saw little changes to the Fort of Mardyck, as it was known. They kept a garrison in the fort and maintained the fortifications, but they made no major modifications. In the end the English period was short-lived because Dunkirk and the surrounding territory were sold to France in 1662, after just four years. From the 1670s to the end of the 17th century the French king Louis XIV invested huge sums in transforming Dunkirk into a major naval base and fortress. His fortifications expert Vauban judged the Fort de Mardyck superfluous as it stood on the wrong side of Dunkirk to guard against a Spanish attack. The landward fortifications were demolished, although the wooden fort remained until the end of the 17th century.

No trace of the fortifications of the Fort de Mardyck can be seen today. The land fortifications were demolished and built over and the foreshore where the wooden fort stood is now covered by the modern port facilities. The only reminder of the fort’s existence is in the name of the village that stood on the same spot, now a suburb of Dunkirk, which is called Fort-Mardyck.

The 3D models that are shown with this article were created using maps and plans from the various stages of the fort’s history to show what it might have looked like in the 17th century. Where the details are not known representative features from other fortifications have been used to form an impression of how the Fort de Mardyck might have appeared.

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