In response to the formation of the Third Coalition, which united Britain, Russia, and Austria against France, Napoleon moved the troops of the Grand Armée in August. By 30 September they had successfully crossed the Rhine, and by 11 October they had crossed the Danube. Napoleon's army caught General Mack and Archduke Ferdinand's troops unprepared, and Mack's entire army was forced to surrender at Ulm. On 15 November, the French army entered Vienna unopposed. The joint Austro-Russian army, north-east of Vienna, advanced against Napoleon, and the armies fought at Austerlitz. The French won a comprehensive and skilled victory, which showed the French army to be the dominant force in Europe. The Russians retreated, and on 26 December 1805, Napoleon imposed the Treaty of Pressburg on the Austrian empire.

See Michael Broer, Europe under Napoleon 1799-1815 (London: Arnold, 1996), pp. 41-2.