That evening at Beaumont was issued a general order[62] for the forward movement of the army, to commence at half-past two o’clock the next morning, the 15th. For each corps special directions were given, and also for each of the three divisions of the Imperial Guard,—Marshal Mortier, its commander, having through illness been obliged to remain at Avesnes. The 2d Corps, followed by the 1st, was to advance on the left of the army; the 3d and 6th and the Guard on the centre; and the 4th Corps, which was at Philippeville, on the right. Charleroi was stated to be the general objective point of the movement: but Reille was warned that the 2d Corps would probably cross the Sambre at Marchienne, a few miles higher up, and Gérard was by a later order[63][64] directed to cross with the 4th Corps at Châtelet, a little lower down. The sappers were to precede each column to repair the roads and bridges, which had been in the past few months broken up by the French, in order to obstruct the march of the allies, should they cross the frontier. The centre columns were to be preceded by the cavalry of the 3d Corps and by the cavalry-corps of General Pajol. The other three cavalry-corps, under the command of Marshal Grouchy, were to follow the army. (See Map 2.) By the carelessness of the headquarters-staff in sending but one officer to Vandamme, and in not requiring a receipt[65] from him, and by the accident of this officer being thrown from his horse and failing to deliver his message, Vandamme did not get this order in season; he consequently was not able to get the 3d Corps on the road till seven o’clock. This delay was, of course, vexatious, and operated to hinder the movement upon Charleroi, and to render it less decisive than it otherwise would have been. An unhappy incident occurred to the 4th Corps. General Bourmont, who commanded its leading division, deserted to the enemy, accompanied by his staff. Bourmont was an old royalist, but he had apparently given in his unqualified adhesion to the imperial cause. His treason could not but have a very unfortunate effect on the soldiers, creating a feeling of distrust in their officers, particularly in those of high rank. With these deductions, the day of the fifteenth of June was decidedly a successful one for the French. Although the Prussian General Zieten, who, with the 1st Prussian Corps, held the line of the Sambre, having advance-posts on the right or south bank, opposed at all points to the French a skilful and obstinate resistance,[66] the superiority of his adversaries was too decided for a successful stand to be made anywhere.