Having thus passed these extensive lines, which the French commander had vauntingly called Marlborough's _ne plus ultra_, his grace besieged the strong and important fortress of _Bouchain_, situate on the Scheldt, in the taking of which place, difficulties of great magnitude had to be overcome. Marshal Villiers, by a secret march, during the night of the 9th of August, gained possession of the heights of _Wavrechin_, in order to preserve the line of communication which runs from thence, through a morass between the Scheldt and the Senset, to the town of Bouchain, that he might be enabled to relieve the garrison from time to time. The Duke of Marlborough, observing the enemy at work, throwing up entrenchments on the hill, ordered Lieutenant-Generals Cadogan and Fagel to march with a body of troops, of which CADOGAN'S HORSE formed part, to dislodge the French. As the British grenadiers advanced to the attack, his grace rode forwards to reconnoitre the works on the hill; and observing that the entrenchment was a perfect bulwark, strong and lofty, and crouded with men and cannon, he gave orders for the troops to retire. On the following day Marshal Villiers issued from the works with a hundred hussars, to observe the progress of his opponent, and encountered Lieutenant-General Cadogan, who was reconnoitering with a squadron of horse. A skirmish ensued, and four squadrons of French carabineers advanced to aid the marshal. Cadogan, being thus out-numbered, made a precipitate retreat, which occasioned the enemy to pursue with great eagerness. Meanwhile, CADOGAN'S HORSE and two other squadrons, advanced from the camp, and formed up beyond the summit of a rising ground, where they were out of the enemy's sight; and the moment the French carabineers appeared on the top of the hill, they were charged by Cadogan's squadrons with such resolution, that they were immediately broken. Marshal Villiers was in danger of being surrounded and taken prisoner, but a French brigadier-general interposed, with singular bravery, and rescued the marshal. The gallant brigadier was severely wounded and taken prisoner, and most of his men cut down by the British CUIRASSIERS; and Marshal Villiers galloped back with his shattered squadrons with greater haste than he had advanced. Fortifications were afterwards constructed, with a causeway through the inundations, and the communication between the town of Bouchain and the troops on the heights of Wavrechin was cut off. The siege was prosecuted with zeal and energy, and Marshal Villiers and a numerous French army were spectators of the capture of this important fortress. After the works were repaired and the place put in a state of defence, the troops were placed in winter quarters.