This however was prevented by the extreme vigilance of king William.
After the bombardment of Brussels, Villeroy, being-reinforced with all the troops that could be drafted from garrisons, advanced towards Namur with an army of ninety thousand men; and prince Vaudemont, being joined by the prince of Hesse with a strong body of forces from the Rhine, took possession of the strong camp at Masy, within five English miles of the besieging army.

The king understanding that the enemy had reached Fleurus, where they discharged ninety pieces of cannon as a signal to inform the garrison of their approach, left the conduct of the siege to the elector of Bavaria, and took upon himself the command of the covering army, in order to oppose Villeroy, who being further reinforced by a detachment from Germany, declared that he would hazard a battle for the relief of Namur.

But when he viewed the posture of the allies near Masy, he changed his resolution and retired in the night without noise.
On the thirtieth day of August, the besieged were summoned to surrender, by count Horn, who in a parley with the count de Lamont, general of the French infantry, gave him to understand that mareschal Villeroy had retired towards the Mehaigne; so that the garrison could not expect to be relieved.

No immediate answer being returned to this message, the parley was broke off, and the king resolved to proceed without delay to a general assault, which he had already planned with the elector and his other generals.

Between one and two in the afternoon, lord Cutts, who desired the command though it was not his turn of duty, rushed out of the trenches of the second line, at the head of three hundred grenadiers, to make a lodgement in the breach of Terra-nova, supported by the regiments of Coulthorp, Buchan, Hamilton, and Mackay; while colonel Marselly with a body of Dutch, the Bavarians, and Brandenburghers, attacked at two other places.