1. In regard to Napoleon’s action with reference to the defeated Prussians, it is necessary to distinguish between instituting a prompt and vigorous pursuit of them, and taking immediate measures for ascertaining in which direction they had retreated. The first was under the circumstances impossible, that is, without an entire change of plan, but the second was not only possible, but of prime necessity. Charras,[494] however, complains bitterly of Napoleon for not following up the Prussians. “Not to pursue the vanquished, sword in hand, to leave him time to collect himself, to reform his forces, to gather in his reinforcements, was so strange a thing for troops accustomed to the tactics of Napoleon.” But Clausewitz[495] with better judgment says:— “If we seem here to find so great a difference from the earlier methods of procedure adopted by the French, we must get a true picture of the changed conditions. The extraordinary energy in pursuit to which the brilliant results of Bonaparte’s former campaigns were due, was simply pushing very superior forces after an enemy who had been completely vanquished. Now, however, Napoleon had to turn with his main force, and above all with his freshest troops, against a new enemy, over whom victory had yet to be gained. The pursuit [of the Prussians] had to be carried out by the 3d and 4th Corps, the very two who had been engaged in the bloodiest fight till ten in the evening, and now necessarily needed time to get into order again, to recover themselves, and to provide themselves with ammunition.” Napoleon, therefore, while censurable for not having ascertained as early as possible the direction of the retreat of the Prussians, and for not having moved promptly with his main body against the English, can not be blamed for having allowed Grouchy’s troops to remain on the field till noon, to recover from their fatigues. 2. It hardly needs to be said that if Napoleon had known that the Ist and IId Prussian Corps were retiring on Wavre, he would not have ordered Grouchy on Gembloux. Exactly what he would have done, it is needless to conjecture, but in all probability he would have kept the whole army together, or within easy reach, so as to have concentrated an overwhelming force against Wellington the next morning, if not on that afternoon. 3. To illustrate the effect which the concealment of the Bertrand order by Marshal Grouchy has produced on the mind of an able critic, take the following passages from Clausewitz,[496] who wrote his narrative before the order came to light:—