Sixteen thousand of the Spanish troops under the order of the archduke were encamped to the west of the town, and had 30 of their siege-guns in position there, while 4000 men were stationed on the east of the town under Count Bucquoy. Ten guns were in position on that side. Ostend had no natural advantages for defence beyond the facility of letting the sea into the numerous channels and ditches which intersected the city, and protected it from any operations on the south side. On the east the Geule was broad and deep, and an assault from this side was very difficult. The Old Haven, on the west side, was fast filling up, and was fordable for four hours every tide.

This, therefore, was the weak side of the town. The portion especially exposed to attack was the low sandy flat on which the old town stood, to the north of Ostend. It was against this point, separated only from the enemy's position by the shallow Old Haven, that the Spaniards concentrated their efforts. The defence here consisted of a work called the Porc-Espic, and a bastion in its rear called the Helmond. These works lay to the north of the ditch dividing the old from the new town, while on the opposite side of this ditch was a fort called the Sand- hill, from which along the sea face of the town ran strong palisades and bastions.