Capitulation of Ulm

On 26 August 1805 the Army of the Ocean Coasts left Boulogne: seven corps took the eastward road by separate routes, with stages calculated in advance by Berthier. In thirty-five days two hundred thousand men crossed the Rhine on a two-hundred-kilometre front between Mainz and Strasbourg, without Vienna grasping where the blow would fall.

General Mack, with seventy thousand Austrians, waited for the French in the Black Forest gap and thought he had time: Kutuzov's Russians were marching to join him. Napoleon did not attack him frontally. He wheeled his whole army south-east, crossed the Danube downstream at Donauwörth and Neuburg, and cut the line of retreat on Vienna.

The actions at Wertingen, Günzburg and Elchingen tightened the net; Ney stormed the Elchingen bridge on 14 October. Mack, encircled in Ulm without supplies or hope of relief, capitulated on the 20th: some thirty thousand men filed past the Emperor and laid down their arms.

All told, the Ulm campaign cost Austria nearly sixty thousand men for a few thousand French casualties, almost without a pitched battle. It was the purest demonstration of the Napoleonic system: the march, not the shock, decides.

The road to Vienna lay open; the city was occupied on 13 November. But the day after the capitulation, Trafalgar closed the sea for good: the Empire won the continent on the day it lost the ocean.