The tremendous roar of Artillery in the direction of Ligny gave a sufficient intimation to the Duke that a great Battle had taken place in that quarter, but as it seemed to continue stationary, and only ceased as night set in, he was doubtful of the result, and remained in this state of suspense and uncertainty until the following morning; the Officer who had been despatched in the night to Quatre Bras from the Prussian Head Quarters with the expected communication, having been surprised in the dark, and made a prisoner by the French. [Illustration:] CHAPTER VI. Prince Blücher having ascertained, on the morning of the 16th, that his communication with the Left Division of the Duke of WELLINGTON's forces by Quatre Bras continued uninterrupted, resolved upon accepting battle in the position in rear of Fleurus, which had been previously fixed upon as the one most eligible, in the event of the Enemy's adoption of that line of operations respecting which all doubt and uncertainty had now ceased. Its importance in a strategical point of view, apart from tactical considerations, was manifest. WELLINGTON having, on his part, selected Quatre Bras as the point whereon to concentrate his forces, the position in question, connected as it was with the latter by a paved road over an extent of not more than six or seven miles, offered great facility for co-operation and mutual support upon whichever point the great mass of the French Army might be directed. Should it prove tenable, then, considered in conjunction with the advance of the Russians from the Rhine, the whole line of the Meuse below Namur, and the communications with Aix la Chapelle and the Prussian States, were effectually secured. If, on the other hand, either position should be forced by the Enemy, then Mont St Jean and Wavre, upon parallel lines of retreat towards Brussels and Louvain, would likewise offer the means of co-operation on the south side of the Forest of Soignies; and supposing BLÜCHER willing to risk for a time his communication with the right bank of the Meuse, concentric lines of retreat upon Brussels would bring the two Armies in combined position in the immediate front of that capital. Supposing also that NAPOLEON's plan had been to advance by Mons, the concentration of the Prussian forces could not have been effected upon a more favourable point than that of Sombref, whence they could have advanced in support of their Allies, leaving a sufficient portion of ZIETEN's Corps to watch the approaches by Charleroi: and, finally, had the French Emperor directed his main attack by Namur, the retreat of THIELEMANN's Corps would have secured time for effecting the concentration of the First, Second, and Third Prussian _Corps d'Armée_, if not also of the Fourth, while the Duke of WELLINGTON's forces might have assembled at Quatre Bras, for the purpose of meeting any secondary attack from the Charleroi side, and of forming a junction with the Prussian Army.