When Napoleon's corps threatened to envelop Mack's army, the Austrian general unwisely held his ground near the city of Ulm.

After receiving orders to seize the Danube bridges, Marshal Michel Ney sent Malher to capture the crossing at Günzburg.

Discouraged by the encounter, Mack ordered his soldiers to march back to Ulm which is 22 kilometers west-southwest of Günzburg.

Austria, defeated by France in the War of the Second Coalition and forced to accept a French client state in Italy, planned to take revenge.

The head of the Austrian army, Feldmarschall Archduke Charles, Duke of Teschen believed his soldiers were not ready for war, but the pro-war faction at the court of Emperor Francis I of Austria outmaneuvered him.

[1] Feldmarschall-Leutnant Karl Mack von Lieberich, who had the full confidence of the emperor, became largely responsible for developing Austria's war plan.

[3] Foreseeing trouble with Mack's plan, Charles talked the emperor into transferring 30,000 soldiers from Italy to Germany, but these troops would arrive too late to remedy the situation.

[6] On 8 September, the army of Archduke Ferdinand invaded the Electorate of Bavaria, with a plan to defend the line of the Lech River.

[7] Mack changed the plan on 12 September and insisted that the army continue to advance farther west to the Iller River.

Ferdinand and the army chief of staff General-major Anton Mayer von Heldensfeld both opposed the move and appealed to the emperor.

Lannes corps and part of Murat's cavalry advanced directly east into the Black Forest to trick the Austrians into believing it to be the main attack.

[11] Meanwhile, Jellacic's troops held a line farther south near Biberach an der Riß where they were watching the Black Forest.

On 8 October, Lannes and Murat marched southwest and collided with Feldmarschall-Leutnant Franz Xaver von Auffenberg's division in the Battle of Wertingen.

[16] On this day, Soult marched toward Aichach and Davout reached the Danube at Neuburg an der Donau, while Bernadotte and Marmont arrived at Ingolstadt.

[15] Ney marched to Donauwörth,[17] but he never crossed the Danube and instead moved west to Giengen[15] while following orders to proceed to Ulm.

[18] At this time, Mack and Ferdinand deployed a significant part of their army on a line from Reisensburg, just east of Günzburg on the Danube, to Limbach which lies five kilometers to the southeast.

General-major Konstantin Ghilian Karl d'Aspré commanded a force on the north bank designed to watch for the French and protect the bridges.

The western column under Colonel Étienne Nicolas Lefol moved to Leipheim[21] but he abandoned the effort when the street led into a marsh[22] (now the Badesee Günzburg and Mooswaldsee).

[note 1] The central column led by General of Brigade Pierre-Louis Binet de Marcognet moved directly south toward the two main Günzburg bridges.

[23] The Austrians lost six guns and 2,000 casualties including d'Aspré captured[16] and Major Franz Muller of the Kaunitz Regiment killed.

[26] Ney reported to Napoleon that both Mack and Ferdinand had been at Günzburg on the 9th and suggested that a strong enemy force lay at Ulm.

Napoleon then ordered Ney to attack Ulm, not understanding that he was sending a single corps against the entire Austrian army.