He gained, it is true, the support of Saxony and Weimar; but this brought less than 21,000 men to his side.
On the other hand, Napoleon, as Protector of the Rhenish Confederation, secured the aid of 25,000 South Germans, as well as an excellent fortified base at Wuerzburg.

His troops, holding the citadels of Passau and Braunau on the Austrian frontier, kept the Hapsburgs quiet; and 60,000 French and Dutch troops at Wesel menaced the Prussians in Hanover.

Above all, his forces already in Germany were strengthened until, in the early days of October, some 200,000 men were marching from the Main towards the Duchy of Weimar.

Soult and Ney led 60,000 men from Amberg towards Baireuth and Hof: Bernadotte and Davoust, with 90,000, marched towards Schleitz, while Lannes and Augereau, with 46,000, moved by a road further to the left towards Saalfeld.
The progress of these dense columns near together and through a hilly country presented great difficulties, which only the experience of the officers, the energy and patience of the men, and the genius of their great leader could overcome.

Meanwhile Napoleon had quietly left Paris on September 25th.