A second Officer, Lieutenant Massow, had been despatched from the Prussian to the Anglo-Allied Head Quarters; and it was about this time that he reached the Duke, with a verbal communication respecting the retreat upon Wavre, and the position intended to be assumed in that quarter. It was of a nature which, taken altogether, was so far satisfactory, that Wellington immediately sent a verbal message by this Officer to Blücher, acquainting him with his intended retrograde movements, and proposing to accept a battle, on the following day, in the position in front of Waterloo, provided the Prince would detach two Corps to his assistance.
The following is the manner in which the retreat of the Anglo-Allied Infantry, then in full operation, was executed. It was an important matter to mask the retreat as much as possible, so as to gain time for the free and unimpeded movement of the Army along the high road leading to the position in front of Waterloo. For this purpose, the Light Troops continued to maintain the line of Outposts, until their respective Supports, which had remained stationary sufficiently long to conceal the retreat of the troops in their rear, began also to retire.
The First and Fifth British Divisions, and the Second Dutch-Belgian Division, as also the Brunswick Corps, effected their retreat in excellent order, notwithstanding the delay that was created by the narrowness of the bridge and street of Genappe. Their retreat was covered by Alten's Division, to which were added for this purpose, the 1st Battalion of the 95th British Rifles, the 2nd and 3rd Brunswick Light Battalions, the Brunswick Advanced Guard Battalion, and the Light Companies of Byng's Brigade of Guards.
The main body of Alten's Division commenced its retreat about eleven o'clock. Ompteda's Brigade of the King's German Legion was withdrawn to Sart à Mavelines, which it immediately occupied, as also the Wood of Les Censes in its front. Halkett's British Brigade then retired secretly until it reached some favourable ground, a little distance in rear of Ompteda's Brigade, upon which it was immediately drawn up. Kielmansegge's Hanoverian Brigade was withdrawn still further to the rear, and occupied a third position. Thus posted, the Division was ordered, in the event of being attacked, to retire by Brigades alternately.
It was a little before midday when the Light Troops of Alten's Division began to retire. They occupied the advanced line, commencing from the southern extremity of the Wood of Bossu on the right, extending along Gemioncourt and the inclosures of Piermont, and crossing the Namur road on the left: from which line they gradually and slowly fell back upon Ompteda's Brigade, in a manner evincing admirable skill, steadiness, and regularity.
In order more effectually to mask the movements on the Allied side of the Namur road, the whole of the Cavalry was drawn up in two lines immediately contiguous to, and in rear of, that road; the Heavy Cavalry forming the Second Line, and Picquets being thrown out from the First Line, to relieve those of the retiring Infantry.
The main body of Alten's Division now commenced its further retreat; but not by alternate Brigades, this mode having been directed only in the event of an attack; the latter retired successively in the order in which they stood, preserving their relative distances, so that they might commence the alternate system of retreat, if attacked. To facilitate the passage of other portions of the Army through the narrow defile of the bridge and town of Genappe, this Division retired by Bezy, and crossed the Genappe, lower down the stream, by the bridge of Wais le Hutte.
In the early part of the morning, Ney had, like his opponent, been ignorant of the result of the Battle of Ligny; but he was aware that the Anglo-Allied Army had been considerably reinforced during the night, principally by the arrival of its Cavalry.