Nevertheless, the Emperor had substantially gained his point. Almost without any real fighting, and in spite of the clumsy working of his great military machine, he now had 124,000 men encamped near the point of junction between the allied armies, ready to strike either. On the night of the 15th, when, at Charleroi, Napoleon examined the reports sent in by Grouchy and Ney, he reached a conclusion that was wrong, but which, fastening itself on his mind, could never be shaken, and contributed vastly to his ruin. He believed, judging from the direction in which the Prussians had retreated, that they were retreating upon Liege, their natural base of operations, instead of adhering to the design of so conducting their retreat as to be at all times in reach of the English. The various delays of the French, and their failure to advance as far as the Emperor’s orders had directed, made it possible for the indefatigable Blücher to bring up a large part of his army, and instead of retreating on his base,--as Napoleon thought he would do,--Blücher advanced to Sombreffe to give battle. Toward morning, in the night of the 15th, the Prussians had evacuated Fluerus. Grouchy took possession of it, and the Emperor reached it shortly before noon. Going to the tower of a brick mill, which stood at the end of Fluerus, Napoleon had the roof breached and a platform made, upon which he could stand and view the various positions of the enemy. The willingness of the Prussian commander to fight was partly the result of Wellington’s diplomacy. The Englishman had been caught napping, and to secure time to concentrate his badly scattered forces he had given Blücher a written promise to support him. It was extremely necessary to Wellington that Blücher should stand between the English army and the French, and fight them off, until the English could get themselves together. Besides, if Blücher retreated upon Liege, the English army would be left alone before Napoleon. In that event it would have to fight with inferior forces, or fall back on its base of operations, leaving Brussels to be occupied by the Emperor. In 1876 there was found in the Prussian archives the letter in which Wellington encouraged his ally to make a stand. This letter was sent from the heights north of Fresnes, about two miles south of Quatre Bras, at half-past ten o’clock in the morning of the 16th. In this much-debated letter the wily Englishman misrepresents the positions of his own troops, puts them some hours nearer to the scene of action than they really were, and assures Blücher of their support if he will stand and fight. Wellington tells Blücher that he will at least be able to effect such a powerful diversion in his behalf that Napoleon will not be able to use against the Prussian more than a moiety of his army.