Napoleon 's lightning campaign exposed the Austrian indecisive command structure and poor supply apparatus . Mack completely misread the French dispositions and scattered his forces ; as the French defeated each unit separately , the surviving Austrians withdrew toward the Ulm fortifications . Napoleon arrived to take personal command of close to 80 @,@ 000 men . At Ulm on 16 October Karl Mack surrendered his encircled army of 20 @,@ 000 infantry and 3 @,@ 273 cavalry . The officers were released on the condition that they not serve against France until formally exchanged for French officers captured by the Austrians , an agreement to which they held .