 To accomplish this objective, Napoleon sent Ney's Corps to Günzburg, completely unaware that the bulk of the Austrian army was heading to the same destination.On 8 October, however, the campaign witnessed its first serious battle at Wertingen between Auffenburg's troops and those of Murat and Lannes.For reasons not entirely clear, on 7 October Mack ordered Franz Xavier Auffenburg to take his division of 5,000 infantry and 400 cavalry from Günzburg to Wertingen in preparation for the main Austrian advance out of Ulm.