Based on my viewing of War & Peace, the Austrian army of the 3rd coalition, under General Mack, was surrounded at Ulm and then surrendered.
But why was he surrounded? Why didn’t he move his army back? And if surrounded, why not fight through (if insufficient supplies)? Or hold out there for the Russian and other 3rd coalition forces to arrive, which were on the march?
It seems like the history books give me the conclusion that there wasn’t much fighting, which seems strange to surrender so quickly without more bloodshed.