At ten o'clock in the evening of Saturday the 17th, twenty-four hours after the battle of Ligny, and at the moment when the whole body of the Prussian forces was already reunited in an orderly circle round Wavre, Grouchy, twelve miles to the south of them, was beginning--but only beginning--to discover the truth. He wrote at that hour to the Emperor that "the Prussians had retired in several directions," one body towards Namur, another with Blucher the Commander-in-chief towards Liège, _and a third body apparently towards Wavre_. He even added that he was going to find out whether it might not be the larger of the three bodies which had gone towards Wavre, and he appreciated that whoever had gone towards Wavre intended keeping in touch with the rest of the Allies under Wellington. But all that Grouchy did after writing this letter proves how little he, as yet, really believed that any great body of the enemy had marched on Wavre. He anxiously sent out, not northward, but eastward and north-eastward, to feel for what he believed to be the main body of the retreating foe. During the night he did become finally convinced by the mass of evidence brought in by his scouts that round Wavre was the whole Prussian force, and the conclusion that he came to was singular! He took it for granted that through Wavre the Prussians certainly intended a full retreat on Brussels. He wrote at daybreak of the 18th of June that he was about to pursue them. That Blucher could dream of taking a short cut westward, thus effecting an immediate junction with Wellington, never entered Grouchy's head. He did not put his army in motion until after having written this letter. He advanced his troops in a decent and leisurely manner up the Wavre road through the mid hours of the day, and himself, just before noon, wrote a dispatch to the Emperor; he wrote it from Sart, a point ten miles south of Wavre. In that letter he announced "his intention to be massed at Wavre _that night_," and begging for "orders as to how he should begin his attack of the _next day_." The next day! Monday! Already, hours before--by midnight of Saturday--Blucher had sent his message to Wellington assuring him that the Prussians would come to his assistance upon Sunday, the morrow. Even as Grouchy was writing, the Prussian Corps were streaming westward across country to appear upon Napoleon's flank four hours later and decide the campaign. Having written his letter, Grouchy sat down to lunch. As he sat there at meat, far off, the first shots of the battle of Waterloo were fired. * * * * *