It was ten o'clock at night when the first intelligence of the attack made by the French in the direction of Frasne, was received at the Prince of Orange's Head Quarters, at Braine le Comte. It was carried by Captain Gagern, who, as previously mentioned (see page 70), had been despatched by Prince Bernhard of Saxe Weimar, with his Serene Highness's report of the affair, to General Perponcher at Nivelles, and who was subsequently sent on by the General, with this information to the above Head Quarters. Lieutenant Webster, Aide de Camp to the Prince of Orange, started soon afterwards for Brussels, with a report from the Dutch-Belgian Quartermaster General, de Constant Rebecque, stating what had taken place, and detailing the measures which he had thought proper to adopt. These measures did not entirely coincide with the instructions above given, as issued by the Duke, because they were consequent upon the affair at Frasne, with which his Grace at that time was unacquainted; but they were perfectly consistent with the spirit of those instructions, inasmuch as they were not adopted "until the Enemy's attack upon the Right of the Prussian Army, and the Left of the Allied Army had become a matter of certainty." The Enemy's advance along the Charleroi road had already been successfully checked at Quatre Bras, and the necessity of immediately collecting at this important point, the troops ordered by the Duke "to be assembled that night at Nivelles" was too obvious to be mistaken.
A little before ten o'clock on the same evening, a further communication reached the Duke from Prince Blücher, announcing the crossing of the Sambre by the French Army, headed by Napoleon in person; and the required intelligence from other quarters having arrived almost at the same moment, and confirmed him in the opinion "that the Enemy's movement upon Charleroi was the real attack," he issued, at ten o'clock P.M., the following Orders for the march of his troops to their Left:—Alten's Division to continue its movement from Braine le Comte upon Nivelles. Cooke's Division to move from Enghien upon Braine le Comte. Clinton's and Colville's Divisions to move from Ath, Grammont, and Audenarde, upon Enghien. The Cavalry to continue its movement from Ninhove upon Enghien.
The disposition of the French Left Column, under Ney, during the night of the 15th, has already been shown. The Centre Column of the French Army was thus located—Vandamme's Corps bivouacked in the Wood of Fleurus; Pajol's Corps of Light Cavalry at Lambusart; the Third Light Cavalry Division, under Domon, on the left, at the outlet of the Wood, and the Heavy Cavalry Corps of Excelmans between the Light Cavalry and Vandamme; the Guards bivouacked between Charleroi and Gilly; and Lobau's Corps, together with Milhaud's Heavy Cavalry Corps, lay in rear of Charleroi. The Right Column, consisting of Gérard's Corps, bivouacked in front of the Bridge of Châtelet, which point it had reached during the evening.
The result of the proceedings on the 15th was highly favourable to Napoleon. He had completely effected the passage of the Sambre; he was operating with the main portion of his forces directly upon the preconcerted point of concentration of Blücher's Army, and was already in the immediate front of the chosen position, before that concentration could be accomplished; he was also operating with another portion upon the high road to Brussels, and had come in contact with the Left of Wellington's troops; he had also placed himself so far in advance upon this line, that even a partial junction of the forces of the Allied Commanders was already rendered a hazardous operation, without a previous retrograde movement; and he thus had it in his power to bring the principal weight of his arms against the one, whilst, with the remainder of his force, he held the other at bay. This formed the grand object of his operations on the morrow.
But however excellent, or even perfect, this plan of operation may appear in theory, still there were other circumstances, which, if taken into consideration, would scarcely seem to warrant a well grounded anticipation of a successful issue. Napoleon's troops had been constantly under arms, marching, and fighting, since two o'clock in the morning, the hour at which they broke up from their position at Solre sur Sambre, Beaumont, and Philippeville, within the French frontier: they required time for rest and refreshment; they lay widely scattered between their Advanced Posts and the Sambre; Ney's forces were in detached bodies from Frasne as far as Marchienne au Pont, the halting place of d'Erlon's Corps; and although Vandamme's Corps was in the Wood of Fleurus, Lobau's Corps and the Guards were halted at Charleroi, and Gérard's Corps at Châtelet. Hence, instead of an imposing advance, with the first glimmering of the dawn of the 16th, the whole morning would necessarily be employed by the French in effecting a closer junction of their forces, and in making their preparatory dispositions for attack; an interval of time invaluable to the Allies, by the greater facility which it afforded them for the concentration of a sufficient force to hold their Enemy in check, and to frustrate his design of defeating them in detail.