WELLINGTON, who had, from the first, anticipated that the attacks of Cavalry would be followed up by others, in which that Arm would be combined with Infantry, was fully prepared to meet this contingency, having as soon as he had ascertained that the Enemy was not disposed to attempt any serious movement against his Right Flank, despatched an Order to CHASSÉ to evacuate Braine l'Alleud and its vicinity, and to proceed with his Dutch-Belgian Division, towards the principal scene of action, along the low ground through Merbe Braine. By this means, his Grace, who contemplated reinforcing his First Line with troops from his Second, would be enabled to supply their place in the latter with others of equal strength. CHASSÉ's movement, executed with much judgement, was in a great measure, if not entirely, concealed from the Enemy's observation; and was very skilfully covered by the 2nd Light Dragoons of the King's German Legion, who continued hovering near the Left Flank of the French Army. In the mean time, the attack upon La Haye Sainte had been renewed with the same fury as before. Major BARING on perceiving the advance of the Enemy's Columns, sent an Officer to the position with this intelligence, and repeated his request for ammunition. The Light Company of the 5th Line Battalion of the King's German Legion was sent to his assistance; but the supply of ammunition, of which he stood so much in need, was not forthcoming: and he therefore, after waiting half an hour longer, during which the contest was uninterrupted, despatched another Officer on the same errand. This application proved equally unsuccessful. He received, however, a reinforcement of two Flank Companies from the 1st Regiment of Nassau. The great struggle was again at the open entrance to the Barn; and the French, finding all their efforts to force an entrance so obstinately and successfully frustrated, had recourse to the expedient of setting the place on fire. A thick smoke was soon observed issuing from the Barn. The greatest consternation pervaded the little garrison; for although there was a pond in the yard, there were no means at hand for conveying the water to the point of danger. Major BARING, whose anxiety was extreme, glancing his eye at the large camp kettles borne by the recently arrived Nassauers, instantly pulled one from off a man's back: several Officers followed his example, and filling the kettles with water, carried them in the face of almost certain death, to the fire. The men hesitated not a moment. Every kettle was instantly applied to the same good office, and the fire was fortunately extinguished; though at the sacrifice of many a brave soldier. Several of the men, although covered with wounds, rejected all persuasion to retire. Their constant reply was, "So long as our Officers fight, and we can stand, we will not stir from the spot." At length the Enemy, wearied out by this most resolute and gallant defence, once more withdrew.