The Elector of Hesse-Cassel now espoused Napoleon's cause.

Thus, without meeting any opposition, Bernadotte's columns reached Wuerzburg at the close of September; there the Elector of Bavaria welcomed the Marshal and gave him the support of his 20,000 troops; and at that stronghold he was also joined by Marmont.
In order to mislead the Austrians, Napoleon remained up to September 23rd at St.Cloud or Paris; and during his stay appeared a _Senatus Consultum_ ordering that, after January 1st, 1806, France should give up its revolutionary calendar and revert to the Gregorian.

He then set out for Strassburg, as though the chief blows were to be dealt through the passes of the Black Forest at the front of Mack's line of defence; and, to encourage that general in this belief, Murat received orders to show his horsemen in the passes held by Mack's outposts, but to avoid any serious engagements.

This would give time for the other corps to creep up to the enemy's rear.

Mack, meanwhile, had heard of the forthcoming junction of the French and Bavarians at Wuerzburg, but opined that it threatened Bohemia.[26] Accordingly, he still clung to his lines, contenting himself with sending a cavalry regiment to observe Bernadotte's movements; but neither he nor his nominal chief, the Archduke Ferdinand, divined the truth.