On the other flank, too, things had gone all in favour of Wellington. At noon Napoleon wrote to Ney that troops had been placed at Marbais to second the marshal's attack on Quatre Bras, yet Ney remained quiescent, and Wellington began his retreat unmolested. Thus on Napoleon's arrival only the duke's cavalry screen and some horse artillery remained on the position. As the emperor justly said, Ney had ruined France. This was the fatal mistake of the campaign. Al though Napoleon opened a rapid pursuit as the cavalry screen crumpled up and decamped, yet he failed to entangle the rear guard so deeply as to force the duke to return to its assistance. Also a tropical thunderstorm considerably retarded the French pursuit. Only as the light failed did Napoleon arrive opposite to Wellington's position, and then by a masterly reconnaissance in force he compelled the duke to disclose the presence of virtually the whole army. The French halted between Rossomme and Genappe, bivouacking in the sodden fields.
18.—During the night Wellington heard that Bliicher would bring two corps certainly, and possibly four, to Waterloo, and the duke determined to accept battle. Yet so far was Welling ton from divining Napoleon's plan that he stationed 17,000 men (including Colville's British division) about Hal, 8 m. to his right, to repel a turning movement that he groundlessly antici pated and to form a rallying point for his right in case his centre was broken. By making this detachment the duke ran a very grave risk. But with the 67,600 men and 156 guns which he had in hand, he took up a truly admirable "Wellingtonian position" in front of Mt. S. Jean. He used a low ridge to screen his main position, exposing comparatively few troops in front of the crest. He occupied Hougoumont with detachments of the British Guards and placed a King's German Legion garrison in La Haye Sainte, the key of his position. The duke also took care to distribute the troops so that the indifferent and immature were closely supported by those who were "better disciplined and more accustomed to war." Full arrangements for Bliicher's co-operation were made through General Muffling, the Prussian attache on the duke's staff.
The duke was to stand fast and receive the attack, whilst Blucher closed round Napoleon's exposed right. Thus the Prussians were the real general reserve on this day.
Blucher kept his promise loyally, but the execution was faulty. The Prussians did not start marching at dawn, and the rear corps (Billow) was selected to lead the column. A fire that broke out in Wavre further delayed the march. But, despite his hurts, the old marshal was in the saddle.
Luckily the wet state of the ground (largely cornfields) and the scattered bivouacs of the French caused Napoleon's attack to be put off until 11.3o A.M. Grouchy had reported at io P.M., 17th, from Gembloux that the Prussians were retiring towards Wavre and Perwez. He stated that he meant to follow the Wavre column, if it was the stronger, and separate it from Wellington. But this was impossible. Grouchy was outside the Prussian left and, by following it, he must inevitably drive the allies together. The emperor answered the letter at 10 A.M., and directed the marshal to march for Wavre. Napoleon's original plan must be kept in mind when considering this letter. It will then be seen to mean that Grouchy was to place his force on Bliicher's inner flank and hold him back from Waterloo. But this is just what the letter does not state precisely; accordingly Grouchy (as Ney had done previously) misread it.
Meanwhile the French army formed up some 1,300 yards from Wellington's position. Although some misgivings filled the minds of such Peninsular veterans as Soult, Reille, and Foy, none assailed Napoleon. But the late hour at which the battle opened, and Napoleon's determination to break Wellington's centre instead of outflanking his left and farther separating the allies, deprived him of any chance of beating Wellington before BlOcher could intervene, Napoleon drew up his army of 74,000 and 246 guns in three lines in full view of the Anglo-Dutch army. It was an imposing array of veteran troops backed by the dark masses of the Imperial Guard. As their emperor rode along the lines the troops acclaimed him with extraordinary enthusiasm.