GÉRARD then declared his opinion to be in favour of the expediency of marching in the direction of the cannonade, in order to connect the movements of the detached force more closely with NAPOLEON's operations; and offered to lead his own Corps towards the Battle. This measure was opposed by the Marshal, as also by General BALTUS, of the Artillery, who represented the difficulties of a march in which this Arm might be compromised. On the other hand, General VALAZE, Commanding Engineer of GÉRARD's Corps, after having coincided in the opinion expressed by the latter, observed that he had three Companies of Sappers, by aid of which he could remove many obstacles. GÉRARD then gave his assurance that he could at all events move on with the gun carriages and limbers. GROUCHY, however, stated his determination to act in conformity with his instructions; which were, to pursue and attack the Prussians, and never to lose sight of them. It had just been intimated to him that his troops had come up with a Rear Guard of the Enemy's Infantry, and he did not consider his information was sufficient to warrant the conclusion that BLÜCHER was drawn up, in expectation of being attacked by him at Wavre; or that he would continue his retreat upon Brussels; or, that if, in manoeuvring to effect his junction with WELLINGTON, he would do so in front, or in rear, of the Forest of Soignies. He has since declared, that he did not deem it his duty to follow the counsel given by GÉRARD, but to attack the Prussians; that to effect the proposed movement with the whole of his forces would have been acting contrary to his Orders; that to have detached only a portion of those forces in the direction of the Forest of Soignies, would have been to separate the two Corps of his Army by a river, whose waters were swollen by the rain, and whose banks were swampy, and thus have rendered their mutual support impossible, however essential it might have become; finally, that a war of inspiration appertains alone to the General in Chief, and that his Lieutenants must confine themselves to that of execution. Hence the march to Wavre was continued. Whilst proceeding to the Advanced Guard, GROUCHY received the despatch, dated from the Farm of Caillou, the 18th of June, at ten o'clock in the morning, acquainting him that the Emperor was going to attack the Anglo-Allied Army, in its position at Waterloo; desiring him to direct his movements upon Wavre in such a manner as to draw his forces nearer to those of NAPOLEON, and, especially, to keep up a close communication with the latter.