The enemy understanding that this general was on his march, determined to reduce Oudenarde, the only pass on the Schelde possessed by the confederates; and invested it on the ninth day of July, hoping to subdue it before the allies could be reinforced.

The duke of Marlborough was immediately in motion, and made a surprising march from Asche, as far as Herselingen, where he was joined by the reinforcement.
Then he took possession of the strong camp at Lessines, which the French had intended to occupy in order to cover the siege of Oudenarde.
Thus disappointed, the French generals altered their resolution, abandoned Oudenarde, and began to pass the Schelde at Gavre.

The two generals of the confederates were bent upon bringing them to an engagement.

Cadogan was sent with sixteen battalions and eight squadrons to repair the roads, and throw bridges over the Schelde below Oudenarde.
The army was in motion about eight o'clock, and marched with such expedition, that by two in the afternoon the horses had reached the bridges over which Cadogan and his detachment were passing.

The enemy had posted seven battalions in the village of Heynem, situated on the banks of the Schelde, and the French household troops were drawn up in order of battle on the adjacent plain, opposite to a body of troops under major-general Bantzaw, who were posted behind a rivulet that ran into the river.