When, therefore, Wellington so suddenly launched forth Vivian's Hussar Brigade against Napoleon's Reserves, then posted close to La Belle Alliance in the very Centre of the French Army; and also pushed forward Adam's Light Infantry Brigade past the Farm and Orchard of La Haye Sainte towards the eminence on which stood the three rallied Squares of the Imperial Guard; he completely turned the Left of d'Erlon's Corps: and by means of the brilliant success which attended these movements, he gradually established himself in rear both of d'Erlon and of Lobau; the latter of whom was still defending himself against Blücher's advance.
In like manner, the Columns of Reille's Corps, comprising the Left Wing of the French Army, and which were advancing through, and contiguously to, the Hougomont inclosures, were turned in their Right Flank.
Thus, by this bold and masterly manœuvre, the whole Front Line of the French Army, which, a short time before, had presented so menacing an appearance, was thrown into disorder and confusion: and supported as that manœuvre was by the advance, at the right moment, of the Duke's entire Line; any attempt, on the part of the French, to rally and resume the offensive, was entirely frustrated. The firm, decided, and determined attitude which Wellington had assumed, had, in fact, struck terror and dismay into the ranks of his opponent: who, perceiving the hasty and confused retreat of his troops, as also the extreme pressure upon his Right by the formidable and now more general attack on the part of Blücher, became completely paralyzed; and conscious of the utter futility of attempting to stem the torrent, he threw himself for temporary shelter into the Square of the 2nd Battalion of the 2nd Regiment of Chasseurs of the Guard.
The Anglo-Allied Line continued its magnificent Advance; which was in truth a march of triumph, not of attack, since all fled before its approach. In the Centre, Lambert's Brigade, together with the 1st or Royal Scots, crossed to the Charleroi road, and took possession of La Haye Sainte; which was found entirely abandoned to the wounded and the dying, who constituted its sole but numerous occupants. The troops that had stood in rear of Hougomont, now poured into its inclosures, aiding and supporting those who had so bravely maintained that important Post in completely clearing it of its assailants; as many of the latter in the Wood, ignorant of what was passing in the open Field, still endeavoured to hold their ground. The Light Troops on the right of Hougomont crossed the Nivelles road without opposition: not only the Infantry in their front having retired, but Piré's Light Cavalry Brigade, which had formed the extreme Left of the French Army during the whole day, having been ordered to proceed to the rear of the Centre to cover the general retreat.
The extreme Left of the Line was flanked by the Prussian Regiments of Cavalry, belonging to Zieten's Corps, previously mentioned as having joined shortly before the General Advance; and the Battalions of the First Prussian Infantry Brigade, together with the Nassau Brigade under Prince Bernhard of Saxe Weimar, were pressing up the Heights against the Left of Durutte's Division posted at the apex of the angle of potence on which stood the extreme Right of the French Army. As the Allied Left descended the outer slope of the position, those Columns of d'Erlon's Corps which had advanced to attack it, were hastily retiring; part of them, indeed, along and near the Charleroi road, had already fallen back in disorder the moment they became aware of the defeat of the troops on the other side of that road, and of the advance of Adam's Brigade, by which their Left Flank was completely turned, and their rear most seriously endangered. Durutte's Division, forming, as before observed, the Right of d'Erlon's Corps, and posted in the angle of potence, perceiving in its direct rear, the retreat of the Imperial Guard, followed by British Infantry; as also that of the Columns of its own Corps on its Left, followed by the Anglo-Allied Line; besides the attack of the Prussians in its Front and on its Right, and which was increasing every moment in vigour and effect; at once saw the certainty of its being cut off if it remained in its present attitude: and hence, aware of its own helplessness, it took to flight.
In the next moment the renewed cheering along the Anglo-Allied Left Wing, announced that it had reached and captured the strong Line of Batteries; by the fire of which, maintained during the entire day, its ranks had been so awfully diminished. Zieten's Battalions took possession, also, of the Batteries which had protected the apex of the angle of potence, and which had been covered by Durutte's Division. Notwithstanding the confused retreat of the Flank Columns of d'Erlon's Corps, those which constituted the central portion of his Line had hitherto retired in some little degree of order: but now they began rapidly to dissolve as the Allied Line approached; and, soon spreading out, they broke forth into one general crowd of fugitives.
The flight of these troops immediately along the rear of Lobau's Line, at the very moment of its being most vigorously assailed by the Thirteenth and Fifteenth Infantry Brigades of Bülow's Corps, covered by an overpowering cannonade, involved its ranks in the general panic which had become uncontrollable. The whole Corps rushed wildly into the stream of fugitives which, with overwhelming force, had set in towards Rossomme and Maison du Roi, on the Charleroi road, the direct line of retreat.
By this time (about a quarter past eight o'clock), Adam's Brigade, pursuing its course on the left side of the high road, was ascending the higher ground in rear of La Belle Alliance. Here it fell into the line of fire of one of Bülow's Batteries; which had immediately followed up the retreat of Lobau's Corps, and opened a cannonade from the previous position of the latter, at a distance of about seven hundred yards. Wellington, perceiving that this fire might occasion serious injury to his advancing troops, directed Count de Sales (who was still his sole attendant) to proceed to the Prussian Battery, and cause it to cease firing; its Commanding Officer not being aware that its shot were falling among British troops. Bülow, on becoming acquainted with this circumstance, immediately checked the fire of his Artillery; and, at the same time, ordered the Infantry of his Right to refrain from firing during its forward movement.
The road which leads from the chaussée across the Height in rear of La Belle Alliance, towards Planchenoit, becomes, after a distance of about a hundred yards, a complete hollow way. As it was approached by Adam's Brigade, a Column of Artillery and Infantry, from the French Right, was hastily retreating up that part of it which was in front of the 52nd Regiment, quite unaware of its having fallen into the immediate vicinity of British Infantry. Astonished by the sudden appearance of the latter along the bank, the Column hesitated for a moment what course to adopt. The Infantry at first presented some little show of defence; but soon threw down their arms, dispersed and escaped as best they could. The Artillery made a dash at the opposite bank, but some of the horses of each gun were instantly brought down by a fire from the British, and the attempt failed. The Commanding Officer of the Battery, as if in a fit of desperation, standing in the centre of his guns, waved his sword above his head in defiance. A soldier from the 52nd Regiment sprang forward, parried his thrust, closed with him, threw him on the ground, and bayoneted him. The guns were immediately abandoned.