right flank of the French might have had the same effect that the arrival of the Prussian army had at the great battle two days later. While the concentration of the Second and Third Corps was rapidly progressing behind him, Zieten was occupied with his retreat on Fleurus. At half-past three in the morning of the 15th, the Prussian picquets in front of Lobbes, a village on the Sambre, were driven in by the advanced guard of the French Left Column (this was the head of Reille’s Corps advancing). An hour later, the French opened with artillery on Maladrie, a hamlet about a mile in front of Thuin. It was this cannonade which was heard by the troops of Steinmetz’s Division in Fontaine l’Evêque, and even Zieten at Charleroi heard it. He therefore lost no time in sending reports to both Blucher and Wellington that fighting had actually commenced. His report to Wellington gave the Duke definite news that an attack on Charleroi was imminent, but it did not induce him to alter his plans in any way. For Wellington was still apprehensive of an attack by way of Mons, and he judged that his army was in the best position to meet such an attack. He was unwilling to engage himself in a move eastwards while there was a chance of the French attacking from the westwards. With such a belief, it is clear that Wellington, by concentrating prematurely at Quatre-Bras, which it was his intention to do if Napoleon’s attack should eventually be by the Charleroi-Brussels road, would merely carry out the very move which his enemy would wish. Therefore he awaited more definite news of the French attack on Zieten. But Zieten’s report to Blucher made the Marshal more than ever assured of the wisdom of concentrating at Sombreffe. The retreat of Zieten’s Corps was very ably carried out. The Prussians at Maladrie, after maintaining a stubborn resistance, were finally overpowered, but they retreated in good order on Thuin. Here they joined a battalion of Westphalian Landwehr, and resistance was made until 7 A.M., when, after suffering very heavy losses, the Prussians fell back to Montigny. Here, again, they joined two squadrons of Dragoons, who covered the rest of their retreat to Marchienne. But the French cavalry, under Pajol, pushed on so vigorously, and the small retreating column suffered such severe losses, that, upon arrival at Marchienne, a mere skeleton was left. By this time also the outposts at Lobbes had effected their retreat on Marchienne. General Steinmetz, commanding the First Division of Zieten’s Corps, was now fully aware of the French attack. He therefore sent a staff officer to warn Van Merlen, who commanded the Dutch-Belgian outposts at St. Symphorien between Binche and Mons, and to inform him that he was falling back with his Division upon Charleroi.