“But the moment he learnt that Blücher had turned towards the Dyle, which must have happened in Gembloux in the night between the 17th and 18th, the idea must have shot at once into his mind that this could only be in order to join Wellington, for one does not leave one’s natural line of retreat without reason. From that moment he had to consider it his duty, not to lie at the heels of Blücher’s rear-guard, but to get between him and Bonaparte, in order to be able to throw himself in front of Blücher in case he wanted to march off to his right. According to this, he would have to turn from Gembloux to the Dyle by the shortest road, &c.”
Says Charras:—[586]
“Everything indicated that the most advantageous manœuvre for Blücher was that which would bring him the most quickly near Wellington,—would unite the Prussians to the Anglo-Dutch. Since the opening of hostilities the two allied generals had manœuvred to bring about this union; and it was evident that they were not going to renounce this idea after the defeat of one of their armies; the activity, energy, audacity,—so well known,—of Blücher—the tenacity,—equally well known,—of Wellington, sufficed to guarantee that they would not easily renounce this intention.
“If they should succeed in this, Napoleon would find himself exposed to being crushed under the weight of the two allied armies.
“This catastrophe, the greatest of all misfortunes, Grouchy ought, before everything, to put himself in position to avert, so far as he could do so. Hence it was imperative that he should come as speedily as possible within the sphere of Napoleon’s operations; and hence, also, he must march on Moustier.
“From this point, in fact, better than from any other, he would be equally in position to diminish the consequences of the union of the Prussians and the Anglo-Dutch, if it should already have been effected, or to hinder it, if it should not yet have taken place.”
With these authorities we entirely concur. Marshal Grouchy, as soon as he had made up his mind that Blücher was retiring on Brussels by way of Wavre, should have marched for the bridge of Moustier, and should have started at daybreak.[587] Instead of this, he adhered to the direction of Sart-à-Walhain, although, even if he were proposing to follow Blücher straight to Wavre, Sart-à-Walhain was out of the direct route. It had in fact been selected because it lay to the eastward of the Wavre road. He might have saved from two to four hours by starting at daybreak, but of this he was utterly unmindful. He did not thoroughly reconnoitre with his cavalry towards the Dyle, to see if the enemy were not marching towards the English, although it was certainly his manifest duty to do so.[588] All he did in this direction was to send[589] a staff-officer with a small escort at daybreak or soon after to the bridge of Moustier, to see, apparently, if any Prussian troops had crossed there, but he rejoined Grouchy before Grouchy had arrived at Sart-à-Walhain, that is, before 11 A.M. With this exception the Marshal made absolutely no reconnoissances to his left until he had arrived in front of Wavre.
Somewhere between 10 and 11 A.M. he reached Sart-à-Walhain. Thence he proceeded to Walhain, or, as it is sometimes called, Walhain St. Paul.[590] He alighted at the house of a M. Hollert, the notary of the neighboring village of Nil St. Vincent, who lived in a large house in Walhain known as the Chateau Marette. Here he stopped to write a despatch to the Emperor and to get his breakfast. The cavalry of Exelmans and the 3d Corps under Vandamme had passed this point on the road to Wavre, and had reached or perhaps passed Nil St. Vincent.
The despatch, which is dated Sart-à-Walhain, by an error for Walhain,—11 A.M.,—begins by stating that the Ist, IId and IIId Corps of Blücher’s army are marching in the direction of Brussels. Grouchy subsequently says:—[591]
“This evening I expect to be concentrated at Wavre, and thus to find myself between Wellington, whom I presume to be in retreat before your majesty, and the Prussian army.”