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.  Indeed, so far did they rely on the aid of the Russians as to order back some regiments sent from Italy by the more sagacious Archduke Charles; but 11,000 troops from Tyrol reached the Swabian army.  That force was now spread out so as to hold the bridges of the Danube between Ingolstadt and Ulm; and on October 7th the Austrians were disposed as follows:  18,000 men under Kienmayer were guarding Ingolstadt, Neuburg, Donauwoerth, Guenzburg, and lesser points, while Mack had about 35,000 men at Ulm and along the line of the Iller; the arrival of other detachments brought the Austrian total to upwards of 70,000 men.  Against this long scattered line Napoleon led greatly superior forces.[27] The development of his plans proceeded apace.  Though Prussia had proclaimed her strict neutrality, he did not scruple to violate it by sending Bernadotte’s corps through her principality of Ansbach, which lay in their path.  He charged Bernadotte to “offer many assurances favourable to Prussia, and testify all possible affection and respect for her—­and then rapidly cross her land, asserting the impossibility of doing anything else.”  Accordingly, that Marshal was lavish in his regrets and apologies, but ordered his columns to defile past the battalions and squadrons of Prussia, that were powerless to resent the outrage.[28]

The news of this trespass on Prussian territory reached the ears of Frederick William at a critical time, when the Czar sent to Berlin a kind of ultimatum, intimating that, even if Prussia deserted the cause of European independence, Russian troops must nevertheless pass through part of Prussian Poland.  Stung by this note from his usually passive demeanour, the King sent off an answer that such a step would entail a Franco-Prussian alliance against the violators of his territory, when the news came that Napoleon had actually done at Ansbach what Alexander had announced his intention of doing in the east.  The revulsion of feeling was violent:  for a short space the King declared he would dismiss Duroc and make war on Napoleon for this insult, but in the end he called a cabinet council and invited the Czar to come to Berlin.[29]