Meanwhile the failure at Gergovia had kindled the enthusiasm of the central districts into white-heat. The Aedui, the most powerful of all the tribes, were now at one with their countrymen, and Bibracte became the focus of the national army. The young Vercingetorix was elected sole commander, and his plan, as before, was to starve the Romans out. Flying bodies harassed the borders of the province, so that no reinforcements could reach them from the south. Caesar, however, amidst his conquests had the art of making staunch friends. What the province could not supply he obtained from his allies across the Rhine, and he furnished himself with bodies of German cavalry, which when mounted on Roman horses proved invaluable. In the new form which the insurrection had assumed the Aedui were the first to be attended to. Caesar advanced leisurely upon them, through the high country at the rise of the Seine and the Marne, toward Alesia, or Alice St. Reine. Vercingetorix watched him at ten miles' distance. He supposed him to be making for the province, and his intention was that Caesar should never reach it. The Celts at all times have been fond of emphatic protestations. The young heroes swore a solemn oath that they would not see wife or children or parents more till they had ridden twice through the Roman army. In this mood they encountered Caesar in the valley of the Vingeanne, a river which falls into the Saône, and they met the fate which necessarily befell them when their ungovernable multitudes engaged the legions in the open field. They were defeated with enormous loss: not they riding through the Roman army, but themselves ridden over and hewn down by the German horsemen and sent flying for fifty miles over the hills into Alice St. Reine. Caesar followed close behind, driving Vercingetorix under the lines of the fortress; and the siege of Alesia, one of the most remarkable exploits in all military history, was at once undertaken.