On Thursday, the 15th of June, the French drove in all the outposts on the west bank of the Sambre at daybreak and at length assaulted Charleroi, it being the intention of the Emperor to crush Blucher ere he could concentrate all his own forces,—far less be supported by the advance of Wellington,—and then rush on Brussels. Zietten held out with severe loss at Charleroi; but long enough for the alarm to spread along the whole Prussian line and then fell back on a position between Ligny and Amand, where Blucher now awaited Napoleon's attack at the head of his whole army, except the division of Bulow, which had not yet come up from Liege.
The design of beating the Prussians in detail was not a success but the second part of the plan—that of separating them wholly from Wellington, might still succeed. With this view, while Blucher was concentrating his force about Ligny, the French held the main road to Brussels from Charleroi, beating some Nassau troops at Frasnes, and following them as far as Quatre-Bras, a farm-house, so-called because it is there that the roads from Charleroi to Brussels, and from Nivelles to Namur cross each other.
On Thursday a Prussian officer arrived at Wellington's headquarters in Brussels, with the intelligence of Napoleon's decisive operations. It is still an open question just what hour this news was received by the Duke, the time being variously stated at from 1 to 6 o'clock p.m. This news was to the effect that the attack had commenced and the outposts of the Allies had been driven back—much to Wellington's surprise, as he was not wholly prepared for the news. There was to be a ball in Brussels on Thursday evening, at the Duchess of Richmond's hotel, attended by the Duke of Wellington and most of his general officers. Notwithstanding the intelligence, they all went; but a second dispatch arrived at 11 o'clock, announcing that "the French had entered Charleroi that morning, and continued to march in order of battle on Brussels; that there were one hundred and fifty thousand strong; and that the Emperor was at their head!" It was now but too clear that no more time should be lost and the Duke and all of his officers hurried out of the ball-room.
Wellington, now fully aware of his situation, at once issued orders for the breaking up of his cantonments, and the concentration of the forces, which were spread over a very great extent. He rode off at an early hour on the 16th, to Quatre-Bras, to visit the position, and thence to Bry, where he had an interview with Blucher.
Napoleon, whose manoeuvres had thus far succeeded to his wish, on coming up from Charleroi about noon on the 16th, was undecided whether Blucher at Ligny, or Wellington at Quatre-Bras, ought to form the main object of his attack. He at length determined to give his own personal attention to Blucher.
The advanced guards met at the village of Fleurus, and those belonging to the Prussians having retreated, their army now appeared drawn up in battle array;—their left on Sombref; their centre on Ligny; their right on St. Amand. The reserves were on the heights of Bry. Upon the summit of this high ground the mill of Bry was conspicuous, and behind the mill, in a depression, stood the village of Bry, whose steeple only was visible.
The Prussian forces occupied a line nearly four miles in extent. The French army, not including Ney's division, amounting to 60,000 men, halted and formed. The Emperor now rode to some windmills on the chain of outposts on the heights, and reconnoitred the enemy.
The Prussians displayed to him a force of about 80,000 men. Their front was protected by a deep ravine; but their right was exposed, and had Ney's division at Quatre-Bras, as the Emperor supposed, in the rear. A staff officer now arrived from Ney, to inform Napoleon that he had not yet occupied Quatre-Bras, in consequence of reports which made him apprehensive of being turned by the enemy; but that he would advance, if the Emperor still required it. Napoleon blamed him for having lost eight hours, repeated the order, and added that, as soon as Ney had made good that position, he (Ney) was to send a detachment by the causeway of Namur and the village of Marchais, whence it should attack the heights of Bry in the Prussian rear. Ney received this order at 12 o'clock, noon; his detachment might reach Marchais by about 2 o'clock.
At this latter hour, therefore, the Emperor having descended from the heights whence he had formed a correct view of his position, gave orders for an immediate attack by a change of the whole front, divided into several columns, on Fleurus. The attack extended all along the line of the enemy, and which would be enclosed between two fires on the arrival of the detachment from Ney's division in the rear of the Prussians. "The fate of the war," said Napoleon, in answer to a question from Count Gérard, "may be decided in three hours. If Ney executes his orders well, not a gun of the Prussian army will escape." The soldiers had hardly advanced a few paces, amid vociferous cries of "Vive l'Empereur!" when terrible ravages were made in their ranks by the chain-shot from the village and the balls from the batteries above. A single ball killed eight men in one of the columns. But the enthusiasm of the troops, all eager for battle, was too great to cause them to waver and they advanced almost without firing, drove the Prussians at the point of the bayonet from their positions in the gardens and orchards, and entered the village after a stout resistance, only to retire a short time later being unable to conquer the masses of infantry drawn up in a semi-circle on a slope which surmounted the hill of Bry. The action at Ligny had commenced a little later but not less aggressively. As Gérard's three columns approached the village of Ligny they were received with such a volley that they were obliged to fall back. A large body of artillery was then thrown forward and riddled the village of Ligny and Gérard's columns again advanced, finally taking possession of the place. This was followed by a series of combats, exceedingly ferocious, as the French gave no quarter nor did they receive any from the Prussians.