Captain Grey directed Lieutenant Bacon to patrol towards the house, while he remained with the remainder of the Troop, concealed from the Enemy's view, a disposition favoured by the nature of the ground, and the trees in the hedges, on both sides of the road. When Lieutenant Bacon's party moved forward, it was discovered by the Vedette, who began circling, and fired his carabine. The French Picquet posted in the house instantly rushed out; several of the men had their jackets and accoutrements off; and the Post could easily have been captured, had the special duty on which the British Patrol was engaged admitted of an attack. The French turned out very quickly and galloped to the rear along the high road, while Bacon's party was recalled. A few French Cavalry galloped up to the Vedette on the Heights, but evinced no disposition to advance.
It had now become sufficiently evident that, commencing from this point, the French were in possession of the Namur road; but the principal object which Sir Alexander Gordon had in view was yet to be attained. The Patrol now retired a little until it reached a cross road, which a peasant pointed out as the Prussian line of retreat. Pursuing this track, the Patrol, within an hour, reached Tilly; where General Zieten, who had been placed in temporary command of the Cavalry, was covering the retreat of the Prussian Army.
After remaining here about a quarter of an hour, during which Sir Alexander Gordon obtained from General Zieten the most ample information respecting the movements of the Prussians, the Patrol commenced its return, at a quick pace, striking into a cross road, which joined the high road at a point nearer to Quatre Bras than the one whence it had quitted it. The Patrol reached Quatre Bras at about half past seven o'clock; and Sir Alexander Gordon immediately reported to the Duke that the Prussians had retreated towards Wavre, that the French occupied the ground on which the Battle had been fought; but that they had not crossed the high road, along which the Patrol had proceeded almost into the immediate vicinity of their Advanced Posts.
This latter circumstance was very remarkable, and served to satisfy Wellington that, either Napoleon's victory had not been followed up with a vigour and an effect, by which the safety of his own Army would have been perilled, or, that it had not been of a character sufficiently decisive to have enabled the French Emperor to avail himself of such a vantage ground.
Having ascertained that the contingency for which, as has already been explained, he was fully prepared, had actually taken place; he instantly decided upon retrograding his troops to a position in front of the point of junction of the roads leading from Charleroi and Nivelles upon Brussels, in which he might rely upon the co-operation of a sufficient portion of Blücher's forces from Wavre with his own, by which he would be enabled to confront Napoleon and his main Army with ample means, and thus attain that great aim and end of all strategy, of "operating with the greatest mass in a combined effort upon a decisive point."
Hence, a change in the direction of the previously ordered movements became necessary, and the following instructions were issued:—
"To General Lord Hill.
"17th June 1815.
"The Second Division of British Infantry to march from Nivelles on Waterloo, at 10 o'clock.
"The Brigades of the Fourth Division, now at Nivelles, to march from that place on Waterloo, at 10 o'clock. Those Brigades of the Fourth Division at Braine le Comte, and on the road from Braine le Comte to Nivelles, to collect and halt at Braine le Comte this day.
"All the baggage on the road from Braine le Comte to Nivelles to return immediately to Braine le Comte, and to proceed immediately from thence to Hal and Bruxelles.
"The spare Musket Ammunition to be immediately parked behind Genappe.
"The Corps under the command of Prince Frederick of Orange will move from Enghien this evening, and take up a position in front of Hal, occupying Braine le Château with two Battalions.
"Colonel Estorff will fall back with his Brigade on Hal, and place himself under the orders of Prince Frederick."
Shortly after the departure of the before mentioned Patrol of the 10th Hussars, along the Namur road, the Duke received some despatches from England, to which he gave his attention; and now that he had satisfied himself as to the real state of things, and issued his Orders for the movements of his distant troops, as also for the retreat of those present in the Field, he laid himself down on the ground near Quatre Bras, covered his head with one of the newspapers he had been reading, which had accompanied those despatches, and appeared to fall asleep.
After remaining some time in this state, he again rose, mounted his horse, and rode a little distance down the Field in front of Quatre Bras. He then looked about through his telescope, and expressed to those about him his astonishment at the perfect stillness of the Enemy, remarking at the same time, "What if they should be also retiring? It is not at all impossible."