He engaged, however, in battle without any hesitation, and attacked the line of the Prussians along the Dyle on every accessible point; to wit, at Wavre, at the mill of Bielge, and at the village of Limale. The points of attack were desperately defended by the Prussians under Thielman, so that Grouchy could only occupy that part of Wavre which was on his own side of the Dyle. About four o'clock, and consequently when the fate of the battle of Waterloo was nearly decided, Grouchy received from Maréchal Soult the only order which reached him during the day, requiring him to manœuvre so as to unite himself to the right flank of the Emperor, but at the same time acquainting him with the (false) intelligence, that the battle was gained upon the line of Waterloo. A postscript informed Grouchy, that Bulow was appearing upon Napoleon's right flank, and that if he could come up with speed, he would take the Prussian _flagrante delicto_.[155]
These orders were quite intelligible. But two things were necessary to their being carried into execution. First, that Grouchy should get clear of Thielman, the enemy with whom he was closely engaged, and who would not fail to pursue the French maréchal if he retreated or moved to his left flank, without having repulsed him. Secondly, it was indispensable he should pass the small river Dyle, defended by Thielman's division, since the road leading through the woods of Chapelle Lambert, was that by which he could best execute his march towards Waterloo. Grouchy redoubled his efforts to force the Dyle, but he could not succeed till night, and then but partially; for the Prussians continued to hold the mill of Bielge, and remained in force within a cannon-shot of Grouchy's position.
In the morning, the maréchal, anxious to learn with certainty the fate of Napoleon, though believing, according to Soult's letter, that he was victorious, sent out reconnoitring parties. When he learned the truth, he commenced a retreat, which he conducted with such talent, that though closely pursued by the Prussians, then in all the animation of triumph, and though sustaining considerable loss, he was enabled to bring his corps unbroken under the walls of Paris. Weighing all these circumstances, it appears that Buonaparte had no right to count upon the assistance of Grouchy, far less to throw censure on that general for not coming to his assistance, since he scrupulously obeyed the orders he received; and when at four o'clock, that of attacking and pressing the Prussian rear was qualified by the directions of Soult, to close up to Buonaparte's right wing, Grouchy was engaged in an obstinate engagement with Thielman, whom he must necessarily defeat before he could cross the Dyle, to accomplish the junction proposed.