Besides these natural defences, the place was also protected by fortifications; which were as well constructed as the best of that period.

There was a strong rampire and many towers.

There was also a detached citadel of great strength, looking towards the sea, and there was a ravelin, called St.Anne's, looking in the direction of Bruges.

A mere riband of dry land in that quarter was all of solid earth to be found in the environs of Sluys.
The city itself stood upon firm soil, but that soil had been hollowed into a vast system of subterranean magazines, not for warlike purposes, but for cellars, as Sluys had been from a remote period the great entrepot of foreign wines in the Netherlands.
While the eternal disputes between Leicester and the States were going on both in Holland and in England, while the secret negotiations between Alexander Farnese and Queen slowly proceeding at Brussels and Greenwich, the Duke, notwithstanding the destitute condition of his troops, and the famine which prevailed throughout the obedient Provinces, had succeeded in bringing a little army of five thousand foot, and something less than one thousand horse, into the field.

A portion of this force he placed under the command of the veteran La Motte.