Dunkirk Naval Arsenal
One of the major changes to Dunkirk in the second half of the 17th century was the construction of the Naval Arsenal. In the 1660s the channel where the canals flowed into the sea formed the harbour. On the east side of the harbour lay the town. On the west side there was a large flooded area. Beyond this, a line of fortifications ran from south-west corner of the town up to the sea.
By the 1690s the port of Dunkirk had been transformed into a major naval base capable of sheltering 30 warships in complete safety with the fortress itself. This transformation was achieved by careful management of the waterways and the construction of a huge artificial basin. The water in the basin was kept at a constant level, whatever the tide. Vessels entered via a large lock, 14 metres wide.
All the ground on the west side of the harbour was given over to military use. In addition to the basin itself there were extensive naval stores for provisioning and fitting out the ships. The arsenal, which also occupied some ground on the east side of the harbour next to the town, was surrounded by a small wall for security. Each gate in this wall had a guardhouse to control traffic passing in and out of the arsenal.
One of the greatest assets of the arsenal was that it was situated within the fortress itself, which meant that it was protected from land or sea attacks. The Anglo-Dutch fleet managed to burn several beached ships protected by batteries (at la Hougue in 1692), but any privateers or navy vessels in Dunkirk would be protected by the strong landward fortifications and sea forts.
The arsenalís fortifications were in effect a continuation of the bastioned trace around the town. There were three bastions and their demi-lunes that formed this part of the defences. The central of the three bastions (the Bastion de Madrid), which was the most exposed to attack, was reinforced by a cavalier. Beyond the walls Vauban exploited the wet ground by creating a series of ditches flanked by outlying works. To the north and overlooking the arsenal stood the formidable citadel.