With the first glimmering of daylight the troops, which, under the command of General Jagow, had continued in full possession of Bry and its immediate vicinity during the night, began to retire, firstly, in the direction of Sombref, and thence to Gembloux, which they reached before the arrival of Thielemann's Corps. After the receipt of the Order pointing out the direction of the retreat, Jagow conducted these troops, in the course of the 17th, towards their respective Brigades.
Lieutenant Colonel Sohr, whose Cavalry Brigade with half a Horse Battery, formed the Rear Guard of the line of retreat of Zieten's and Pirch's Corps, received Orders to take up a concealed position between Tilly and Gentinnes, thence to watch the movements of the Enemy; and, as soon as he found himself pressed by the latter, to fall back upon the Defile of Mont St Guibert.
Thielemann, who, it will be recollected, had received a message from Gneisenau, leaving it optional with him to retire by Tilly or Gembloux, according to circumstances, decided on falling back upon the latter point; being well aware that the Enemy was in possession of the Villages of St Amand and Ligny, and of the Field of Battle to within a very short distance from Sombref.
He had collected together his widely disseminated Brigades, and drawn in his Advanced Posts; an operation which, executed in the darkness of the night, retarded his departure so much that it was two o'clock in the morning before the Reserve Artillery, which formed the head of the Column, struck into the road which at Point du Jour, leads from the Namur chaussée to Gembloux. The Rear Guard of this line of retreat, which consisted of the Ninth Infantry Brigade, under Major General Borcke, and the Reserve Cavalry, under General Hobe, and was drawn up along the Namur road, having in its front the Fleurus chaussée, leading directly towards the Enemy, did not commence its march until after four o'clock, when the sun had risen. The main body of the Corps reached Gembloux at six o'clock in the morning.
On approaching this place, Thielemann learned that Bülow had posted the Fourth Corps about three miles in rear of Gembloux, upon the old Roman road; whereupon Major Weyrach, Aide de Camp to Prince Blücher, who had continued with Thielemann during the night of the 16th, set off to seek out the Field Marshal, and to report to him the position and attendant circumstances of the Third and Fourth Corps d'Armée. He soon succeeded in discovering the Prussian Head Quarters at Mélioreux, and communicated the above important information to Count Gneisenau.
Thielemann gave his own Corps a halt on the other side of the town, in order that his troops might obtain rest and refreshment.
The Advance of Bülow's Corps had reached Basse Bodecée, upon the old Roman road, at nightfall of the 16th of June. Here that General became acquainted with the loss of the Battle of Ligny: whereupon he ordered the Brigades of his Corps to be posted at intervals along this road, with the exception of the Thirteenth (under Lieutenant General Hake), which was directed to bivouac more to the rear, near Hottoment, where the same road is intersected by that which conducts from Namur to Louvain.
Both Corps remained for some hours in a state of uncertainty as to the direction to be taken for forming a junction with the First and Second Corps. Thielemann wrote to Bülow that he had received no Orders from Prince Blücher, but that he presumed the retreat was upon St Trond. He also stated that he had not been followed by the Enemy, but that he had heard distant firing on the right, which he concluded was connected with the Duke of Wellington's Army.
At length, about half past nine o'clock, Prince Blücher's Aide de Camp, Major Weyrach, arrived at Bülow's Head Quarters, and brought the Orders for the retreat of the Fourth Corps to Dion le Mont, near Wavre, by Walhain and Corbaix. The Orders also required that Bülow should post the main body of his Rear Guard (which consisted of the Fourteenth Brigade) at Vieux Sart; as also that he should send a Detachment, consisting of one Regiment of Cavalry, two Battalions of Infantry, and two guns of Horse Artillery, to the Defile of Mont St Guibert, to act, in the first instance as a Support to Lieutenant Colonel Sohr, who was at Tilly, and then, upon the latter falling back, to act as Rear Guard in this direction. Lieutenant Colonel Ledebur was accordingly detached upon this duty with the 10th Hussars, the Fusilier Battalions of the 11th Regiment of Infantry and 1st Regiment of Pomeranian Landwehr, together with two guns from the Horse Battery No. 12. The Corps itself moved directly upon Dion le Mont, and on reaching the Height near that town, on which is situated the public house of A tous vents, took up a position close to the intersection of the roads leading to Louvain, Wavre, and Gembloux.