The 1805 war began with the Ulm Campaign, which was disastrous for Austria, with only the corps of Michael von Kienmayer and Franz Jellacic escaping envelopment by the Grande Armée of Napoleon. As Kienmayer's columns fled to the east, they joined with elements of the Russian Empire's army in a rear guard action at the Battle of Amstetten on 5 November. Davout's III Corps caught up with Merveldt's division at Mariazell a few days later. The Austrian soldiers, their morale shaken by continuous retreating, were routed after a brief struggle.
Aftermath
On 12 November, Austria's capital Vienna fell to the French without a fight. The Battle of Austerlitz would decide the war's outcome in early December.