“The Prussian army, having intimation of the enemy’s intentions eight or ten hours before the English, would accordingly be first concentrated. Hopes were even entertained of attacking the Prussians before their four corps were united, or of obliging them to fall back in the direction of Liége and the Rhine, which was their line of operations; and by thus separating them from the English, to create an opportunity for new combinations.
“In these calculations, the characters of the enemy’s commanders were much to be considered. The hussar habits of Marshal Blücher, his activity and decided character, formed a strong contrast with the cautious disposition, the deliberate and methodical manner of the Duke of Wellington. Thus, it was easy to foresee, that the Prussian army would be the first to be concentrated, and also that it would evince more decision and promptitude in hastening to the aid of its ally [than the English army would if the Prussians should be the first to be attacked]. If Blücher had only two battalions ready to act, he would be sure to employ them in support of the English army; but there was reason to believe that Wellington, unless his whole army was united, would not attack the French to succor Blücher. All these considerations rendered it desirable that the attack should be commenced against the Prussian army; it necessarily would, so we thought, be the first to be concentrated, and this turned out to be the fact.”
To the same effect the Emperor says in his “Memoirs”:—[7]
“The [Prussian] army was to assemble in rear of Fleurus. * * * In the night between the 14th and 15th, confidential messengers returned to the French headquarters at Beaumont, and announced that everything was tranquil at Namur, Brussels and Charleroi; this was a happy presage. To have thus succeeded in concealing from the enemy the movements which the French army had made for the last two days, was to have already obtained a great advantage. The Prussian army found itself obliged either to establish a point of concentration further back than Fleurus, or to receive battle in that position without being able to be assisted by the Anglo-Dutch army. * * * All the measures of Napoleon had therefore for their object to attack the Prussians first.”
In a word, Napoleon believed that the allied generals had fixed the points of concentration of their armies too near the frontier for that concentration to be effected in season to oppose to his army an overwhelming force; he thought it very likely also, for the reasons above stated, that he would have only the Prussian army to deal with in the first encounter of the campaign.
There were, to be sure, other courses open to him. He might direct his army upon the communications of the Prussians by passing to the eastward of them and turning their left flank. But this operation involved a wide détour over a difficult country, and in the battle which was certain to result, the Prussian and the English armies would, beyond a doubt, both be united against him. On the other hand he could turn Wellington’s right by moving viâ Lille, Valenciennes or Mons upon Ghent or Brussels. An advance in this direction presented, to be sure, fewer difficulties than the one just spoken of, and promised greater advantages. The Duke himself always maintained that this would have been Napoleon’s best move. It probably would have cut the English communications with Ostend, and would very likely have forced Wellington to evacuate Brussels without a battle, that is, unless he cared to risk an engagement without the aid of his ally. But the Prussians in the meantime would have concentrated without molestation their whole army of 120,000 men, and if Wellington had been successful in avoiding a battle with the French superior force, the two allied generals ought to have been able either to manœuvre Napoleon out of Belgium or to force him to battle on disadvantageous terms. It is probable that in neither of these flanking movements would there be an opportunity afforded for a direct, immediate, crushing blow upon one of the allied armies, such as that which Napoleon thought it very possible that the temerity of Marshal Blücher was going to present to him, if he advanced by way of Charleroi.
We have seen that Napoleon seems to have thought it very likely that Blücher would fight, but, of course, Napoleon could but conjecture what Blücher would do; he could not certainly know that he would not now, as he had done in Germany in 1813, avoid a direct conflict with him, and retire on his base of operations. If Blücher should do this, the two armies, it is true, would be separated and could be dealt with accordingly; but the difficulties of the campaign would be vastly greater than if the Prussian army should be practically disposed of by a decisive victory at the outset. For if the Prussians should fall back without hazarding a battle, they would have to be pursued, certainly far enough to ascertain their real intentions, and to become assured that they were, for the time being at least, definitely separated from the army of Wellington. If this should appear to be the case the question would then arise, which of the two armies should be followed up; and in considering this question, the importance of the occupation of Brussels, at that time the capital of the Netherlands, would naturally influence Napoleon in favor of throwing the bulk of his forces against the Anglo-Dutch. Napoleon, however, as we have already said, seems to have thought it on the whole probable, knowing, as he did, the daring and resolute character of the man, that Blücher would fight, with or without the assistance of the English army, and he also thought that the situation of the English army was such that Blücher would not be likely to get much assistance from it. Napoleon, therefore, hoped to open the campaign with a signal victory, crippling, perhaps destroying, the Prussian army, and he knew that the result of such a victory must be the retreat of the beaten Prussians in a direction certain to separate them entirely and definitely from their English and Dutch allies. The French Emperor would then be free to carry the great bulk of his forces against the English and Dutch. If Wellington stood, he expected to beat him; if he retreated, he would leave Belgium and perhaps Holland at the disposal of the French.
Such, in brief, were Napoleon’s calculations and expectations.