But he was still intent on his Noerdlingen scheme, even after the loss of the Danube bridges exposed his march thither to flank attacks from the four French corps now south of the river.

Nevertheless, Napoleon's miscalculation of Mack's plans, or, as Thiers has striven to prove, a misunderstanding of his orders by Murat, gave the Austrians a chance such as fortune rarely bestows.[30] In spite of Ney's protests, one of his divisions, that led by Dupont, had been left alone to guard the northern bank of the Danube, a position where it might have been overwhelmed by an enterprising foe.
What is more extraordinary, Dupont, with only 6,000 men, was charged to advance on Ulm, and carry it by storm.

On the 11th he accordingly advanced against Mack's fortified camp north of that city.

The Austrians met him in force, and, despite the utmost heroism of his troops, finally wrested the village of Hasslach from his grasp; later in the day a cloud of their horsemen, swooping round his right wing, cut up his tired troops, took 1,000 prisoners, and left 1,500 dead and wounded on the field.

Among the booty was found a despatch of Napoleon ordering Dupont to carry Ulm by storm--which might have shown them that the French Emperor believed that city to be all but deserted.[31] In truth, Napoleon's miscalculation opened for Mack a path of safety; and had he at once marched away to the north, the whole aspect of affairs might have changed.