On the 14th of June, the Dutch-Belgian General VAN MERLEN, who was stationed at St Symphorien, near Mons, and who commanded the Outposts between the latter place and Binche which formed the extreme Right of the Prussians, ascertained that the French troops had moved from Maubeuge and its vicinity by Beaumont towards Philippeville, that there was no longer any hostile force in his front, except a Picquet at Bettignies, and some National Guards in other villages. He forwarded this important information to the Prussian General STEINMETZ, on his left, with whom he was in constant communication, and by whom it was despatched to General ZIETEN at Charleroi. The Prussian General PIRCH II., who was posted on the left of STEINMETZ, also sent word to ZIETEN that he had received information through his Outposts that the French Army had concentrated in the vicinity of Beaumont and Merbes le Château; that their Army consisted of 150,000 men, and was commanded by General VANDAMME, JEROME BUONAPARTE, and some other distinguished Officers; that since the previous day all crossing of the frontier had been forbidden by the French under pain of death; and that a Patrol of the Enemy had been observed that day near Biercée, not far from Thuin. During the day, frequent accounts were brought to the troops of ZIETEN's Corps, generally corroborative of the above, by the country people who were bringing away, and seeking some place of safety for, their cattle. Intelligence was also obtained of the arrival of NAPOLEON, and of his brother, Prince JEROME. ZIETEN immediately transmitted the substance of this information to Prince BLÜCHER and to the Duke of WELLINGTON; and it was perfectly consistent with that which the latter had received from Major General DÖRNBERG, who had been posted in observation at Mons, and from General VAN MERLEN (through the Prince of ORANGE) who, as already mentioned, commanded the Outposts between that place and Binche. Nothing, however, was as yet positively known concerning the real point of concentration, the probable strength of the Enemy, or his intended offensive movements, and the Allied Commanders therefore refrained from making any alteration in their dispositions, and calmly awaited the arrival of reports of a more definite character concerning the Enemy's designs. * * * * * ZIETEN's troops were kept under arms during the night, and were collected by Battalions at their respective points of assembly. Later in the day ZIETEN ascertained, through his Outposts, that strong French Columns, composed of all Arms, were assembling in his front, and that every thing portended an attack on the following morning. ZIETEN's communication of this intelligence reached BLÜCHER between nine and ten o'clock on the night of the 14th.