On 6 July, Marlborough captured the small fortress of Arleux, just to the north of the Lines, west of Bouchain, both to deny its use to the French as a sally-port, and to secure the water supply to Douai, which could be cut off by damming the canal that supplied the town.
On July 6th, Marlborough captured the small fortress of Arleux, located north of the Lines and west of Bouchain. This move was aimed at preventing its use as a sally-port for the French and securing water supplies to Douai by blocking the canal that supplied the town.