Napoleon argued in conference with his generals that he must not attack between the rivers Moselle and the Meuse, because that course would allow Wellington to join Blücher without molestation; nor must he attack between the rivers Sambre and Scheldt, because in that case Blücher would be able to effect a junction with Wellington. Nor, and for similar reasons, did he deem it prudent to descend the Meuse and attack the city of Namur. Napoleon noticed that the Coalition armies would require the longest time to concentrate on their inner flanks, and he decided to attack between the Sambre and the Meuse, to wedge himself in between them, crushing any divisions trying to obstruct his progress. Having the advantage, he planned to manoeuvre rapidly on interior lines, and defeat each army in succession before they could join forces. Napoleon had selected for the line of his main operations the direct road to Brussels, by Charleroi—the road on which Wellington's left wing, and Blücher's right wing rested. As the Prussians' front line covered Charleroi and the French territory immediately to the south of Charleroi, and the Anglo-Allies' most advanced outpost was further up the Charleroi–Brussels road at Frasnes-lez-Gosselies (about north of Charleroi), he planned to first overcome the Prussian army, and then attack the Anglo-allied troops before they could deploy properly. Napoleon's grand object was to prevent the two armies combining and destroy them both; to establish himself in Brussels; to arouse the dense population in Belgium (of which a vast proportion secretly adhered to his cause); to re-annex the country to the French Empire; to excite the desertion of the Belgian soldiery from the service of the Netherlands; to discourage invading armies from crossing the Rhine; perhaps also to enter into negotiations — and most important of all, to gain time to gather and train reinforcements from France. Start of operations (8–12 June) Advance of the French Army of the North The French IV Corps (Gérard's) left Metz on 6 June, with orders to reach Philippeville by 14 June. The Imperial Guard (commanded by Drouot) began its march from Paris on 8 June, and reached Avesnes on 13 June, as did the VI Corps (Lobau's) from Laon. The I Corps (d'Erlon's) from Lille, II Corps (Reille's) from Valenciennes, and III Corps (Vandamme's) from Mézières, likewise arrived at Maubeuge and Avesnes on 13 June. The IV Corps of Reserve Cavalry (Milhaud's)