The so-called Battle of Ulm was not really a battle. Instead, it was a completely overwhelming military manoeuvre that saw Napoleon's army surround that of the Austrians under Karl Mack. Napoleon managed to cut off the Austrian army's supply lines and isolate them within the city of Ulm in Germany, forcing Mack to surrender the entire 27,000-strong force, including eighteen generals. The two forces engaged in some skirmishes as some parts of the Austrian army attempt to escape, but there was no set-piece battle in the normal sense. The surrender knocked Austria out of the War of the Third Coalition.
The shine was taken off Napoleon's great victory when the British won a great sea battle at Trafalgar the following day; yet, on land, the surrender of the Austrians opened up the way for Napoleon's swift capture of their capital, Vienna.