The Anglo-Allied Army had its Right at Mons, and its Left at Binche.
The British Cavalry was cantoned in the villages of Strepy, Thieu, Boussoit sur Haine, Ville sur Haine, and Coegnies; Vivian's Brigade in those of Merbes Ste. Marie, Bienne le Hapart, and Mons: and the Hanoverian Cavalry in those of Givry and Croix. The Reserve was at Soignies.
The Duke of Wellington's Head Quarters were at Binche.
The Prussian Army had its First Corps d'Armée at Beaumont; Fourth Corps at Collerets: Second Corps at Namur, with the exception of the Fifth Brigade, which was on the march to blockade Maubeuge, and bivouacked at Villers: Third Corps was at Gembloux, with its Cavalry bivouacked at Temploux.
Prince Blücher's Head Quarters were at Merbes le Château.
The French Army under Napoleon was completely dispersed. A few of the troops took refuge in Avesnes, others in Guise, and the principal body of them evincing any kind of order, but not exceeding three thousand men, reached Laon.
The French forces under Grouchy were at Dinant. Napoleon quitted Laon for Paris.
On the 21st, the Duke of Wellington crossed the French frontier, moving the principal portion of his Army to Bavay, and the remainder from Mons upon Valenciennes, which Fortress was immediately blockaded; and established his Head Quarters at Malplaquet, celebrated as the scene of the glorious victory gained by the Duke of Marlborough and Prince Eugene over the French under Marshals Villars and Boufflers on the 11th of September 1709.
Both the Allied Commanders had now reached the Triple Line of Fortresses, which, until the Campaign of 1814 proved the contrary, had been considered by so many military men as presenting an insurmountable barrier to the advance of hostile armies into France by its north-eastern frontier. It was most essential that some of the principal Fortresses should be secured; and made to constitute a new basis whence to direct the operations now contemplated against the interior. The following, which first presented themselves on the respective lines of advance of the two Commanders, were destined to be immediately blockaded:—Valenciennes, Lequesnoy, and Cambray, by the Anglo-Allied Army; and Maubeuge, Landrecy, Avesnes, and Rocroi, by the Prussians. The general arrangements for the besieging of the Fortresses, and the planning of the further operations, above alluded to, were to form the subject of a conference to be held very shortly between the Chiefs.
Prince Blücher having, on this day, received reports from Pirch and Thielemann, detailing their proceedings during the two previous days, and showing that Grouchy had succeeded in effecting his escape by Dinant, immediately ordered that the Second Corps d'Armée should move upon Thuin, and place itself under the Orders of Prince Augustus of Prussia; who was to undertake the besieging of the Fortresses to be left in rear of the Prussian Army; and that the Third Corps should march by Charleroi, and follow the First and Fourth Corps as a Reserve.
It will be recollected that Captain Thielemann was sent forward from Namur, with a party of the Pomeranian Hussars, on the night of the 20th, a short distance along the road to Dinant. He was joined at daybreak of the 21st by Lieutenant Colonel Sohr, with the Fusilier Battalions of the 14th and 23rd Regiments, the Brandenburg and Pomeranian Hussars, and five pieces of Horse Artillery; when the whole force followed the Enemy towards Dinant. The latter had, during his retreat, seized every favourable opportunity in narrow and rocky parts of the Defile, to barricade the road, and offer every obstruction to the pursuit: by means of which precaution, and the previous night march, the French contrived to gain so considerably in advance, that Lieutenant Colonel Sohr deemed it prudent, when near Dinant, to forego all further pursuit; and to endeavour to effect a junction with the main body of the Prussian Army, by moving upon Florennes and Walcour. At the former place he halted his Detachment during the night of the 21st; and, in this manner, covered the Left Flank of the main Army.
Anxious to gain intelligence concerning the assembling and marching of the French troops on the left of the Allied Armies, Prince Blücher despatched Major Falkenhausen, with the 3rd Regiment of Silesian Landwehr Cavalry, to scour the country in the vicinity of the road by Rettel to Laon. A Detachment of fifty Dragoons was posted at Bossule le Valcourt, in observation of Philippeville.
The Fourth Corps d'Armée was ordered by the Prince to advance, this day, as far as Maroilles, upon the road from Maubeuge to Landrecies. Its Advanced Guard, under General Sydow, was directed to proceed still further, and to blockade the latter Fortress.
Zieten, in pursuance of Orders which he had received the night before, marched with the First Corps d'Armée upon Avesnes; which Fortress, the Advanced Guard, under General Jagow, was directed to blockade on both sides of the Helpe. The march of the Corps was made in two Columns: the Right, consisting of the First and Second Brigades, proceeded by Semonsies, and halted at the junction of the road from Maubeuge with that from Beaumont to Avesnes; the Left, comprising the Fourth Brigade, the Reserve Cavalry, and Reserve Artillery, marched by Solre le Château, towards Avesnes, and bivouacked near the First and Second Brigades. Two Companies of the Fourth Brigade, with twenty Dragoons, were left to garrison Beaumont; but after the capture of Avesnes, they were ordered to move on to the latter place.