The French troops, when the order for concentration was given, stretched westward as far as Lille, eastward as far as Metz, southward as far as Paris, in the neighbourhood of which town was the Imperial Guard. The actual marching of the various units occupied a week. Napoleon was at the front on the night of the 13th of June; the whole army was upon the 14th drawn up upon a line stretched from Maubeuge to Philippeville, and the attack was ready to begin. The concentration had been effected with singular secrecy, as well as with the promptitude and accuracy we have noted; and though the common opinion of Wellington and Blucher, that Napoleon had no intention of attacking, reposed upon sound general judgment--for the hazard Napoleon was playing in this game of one against two was extreme,--nevertheless it is remarkable that both of these great commanders should have been so singularly ignorant of the impending blow. Napoleon himself was actually over the frontier at the moment when Wellington was writing at his ease that he intended to take the offensive at the end of the month, and Blucher, a few days earlier, had expressed the opinion that he might be kept inactive for a whole year, since Bonaparte had no intention of attacking. By the evening of Wednesday, June the 14th, all was ready for the advance, which was ordered for the next morning. It would but confuse the general reader to attempt to carry with him through this short account the name and character of each commander, but it is essential to remember one at least--the name of _Erlon_; and he should also remember that the corps which Erlon commanded was the _First_ Corps; for, as we shall see, upon Erlon's wanderings with this First Corps depended the unsatisfactory termination of Ligny, and the subsequent intervention of the Prussians at Waterloo, which decided that action. It is also of little moment for the purpose of this to retain the names of the places which were the headquarters of each of these corps before the advance began. It is alone important to the reader that he should have a clear picture of the order in which this advance took place, for thus only will he understand both where it struck, and why, with all its rapidity, it suffered from certain shocks or jerks. Napoleon's advance was upon three parallel lines and in three main bodies. The left or westernmost consisted of the First and Second Corps d'Armée; the centre, of the Imperial Guard, together with the Third and Sixth Corps. The third or right consisted of the Fourth Corps alone, with a division of cavalry. These three bodies, when the night of Wednesday the 14th of June fell, lay, the first at Sorle and Leer; the second at Beaumont, and upon the road that runs through it to Charleroi; the third at Philippeville.