himself, would participate in the Waterloo campaign and had deployed the corps of this army as follows: I Corps (D'Erlon) cantoned between Lille and Valenciennes. II Corps (Reille) cantoned between Valenciennes and Avesnes. III Corps (Vandamme) cantoned around Rocroi. IV Corps (Gérard ) cantoned at Metz. VI Corps (Lobau) cantoned at Laon. I, II, III, and IV Reserve Cavalry Corps (Grouchy) cantoned at Guise. Imperial Guard (Mortier) at Paris. Once the campaign was underway Napoleon, on the evening of 15 June, would send Marshal Ney with the left wing of the army (I and II corps) to face Wellington at Quatre Bras. During the morning of 17 June Napoleon detached the right wing (III and IV corps) under Marshal Grouchy to pursue the retreating Prussians (who retreated to Wavre), while he led the reserves (Imperial Guard, VI Corps, and I, II, III, and IV Cavalry Corps) to rejoin Ney's detachment and pursue Wellington to Waterloo. Coalition forces In the early days of June 1815, Wellington and Blücher's forces were disposed as follows: Wellington's Anglo-allied army of 93,000 with headquarters at Brussels were cantoned: I Corps (Prince of Orange), 30,200, headquarters Braine-le-Comte, disposed in the area Enghien-Genappe-Mons. II Corps (Lord Hill), 27,300, headquarters Ath, distributed in the area Ath-Oudenarde-Ghent. Reserve cavalry (Lord Uxbridge) 9,900, in the valley of the Dendre river, between Geraardsbergen and Ninove. The reserve (under Wellington himself) 25,500, lay around Brussels. The frontier in front (to the west) of Leuze to Binche was watched by Dutch light cavalry. Blücher's Prussian army of 116,000 men, with headquarters at Namur, was distributed as follows: I Corps (Graf von Zieten), 30,800, cantoned along the Sambre, headquarters Charleroi, and covering the area Fontaine-l'Évêque-Fleurus-Moustier. II Corps (Pirch I), 31,000, headquarters at Namur, lay in the area Namur-Hannut-Huy. III Corps (Thielemann), 23,900, in the bend of the river Meuse, headquarters Ciney, and disposed in the area Dinant-Huy-Ciney. IV Corps (Bülow), 30,300, with headquarters at Liège and cantoned around it. The frontier in front of Binche, Charleroi and Dinant was watched by the Prussian outposts. Thus the Coalition front extended for nearly across what is now Belgium, and the mean depth of their cantonments was . To concentrate the whole army on either flank would take six days, and on the common centre, around Charleroi, three days. Start of hostilities (15 June) Napoleon moved the 128,000 strong Army of the North up to the Belgian