But at this time even the Great Duke himself did not know what was going on at any great distance beyond his outposts. Up to the 12th June he had not heard that the French were actually moving towards the Belgian frontier, though he may have suspected it; and so badly served was he by his intelligence officers (who, it is only fair to say, were themselves kept in ignorance of events by the Prussian staff), that it was not until the afternoon of the 15th that he was able to decide whether Napoleon intended to advance on Brussels in one column, by the direct road _viâ_ Charleroi, or whether he would divide his force so as to send a portion of it by the western route through Mons and Hal. Meanwhile Napoleon, with his customary energy, had matured his plans rapidly, and had pushed forward his several corps towards the frontier; so that, when he himself left Paris on the 12th June, he had made up his mind that he would cross into Belgium on the 15th, and be in possession of Brussels shortly afterwards, having defeated Blücher's Prussians and Wellington's British and allied troops. He concentrated rapidly, and on the night of the 14th nearly the whole of his army was in bivouac close up to the Prussian outposts. At dawn on the 15th he saw the first item on his programme carried out, the French forcing back the Prussians, occupying Charleroi, and advancing northwards towards Quatre Bras. At 3 P.M. that day Wellington was apprised of these movements, but so certain was he of the soundness of his dispositions that he feared nothing. Learning that no French troops were moving in the direction of Mons, he knew that his right flank was safe, so at 5 P.M. he issued orders for a general concentration of his force towards Quatre Bras--the point where the Nivelles-Ligny road crossed the road from Charleroi to Brussels--and at 10 P.M. he supplemented these orders by detailed instructions as to routes and objectives. Then he attended the famous ball given by the Duchess of Richmond in Brussels, whereat a great many British officers were present, though all had been warned that they were to leave early and join their regiments marching to the front. Straight from the festive scene, therefore, many rode all night to overtake the troops only as they were becoming engaged with the enemy.