On November 1 Kutuzov had received, through a spy, news that the army he commanded was in an almost hopeless position. The spy reported that the French, after crossing the bridge at Vienna, were advancing in immense force upon Kutuzov's line of communication with the troops that were arriving from Russia. If Kutuzov decided to remain at Krems, Napoleon's army of one hundred and fifty thousand men would cut him off completely and surround his exhausted army of forty thousand, and he would find himself in the position of Mack at Ulm. If Kutuzov decided to abandon the road connecting him with the troops arriving from Russia, he would have to march with no road into unknown parts of the Bohemian mountains, defending himself against superior forces of the enemy and abandoning all hope of a junction with Buxhowden. If Kutuzov decided to retreat along the road from Krems to Olmutz, to unite with the troops arriving from Russia, he risked being forestalled on that road by the French who had crossed the Vienna bridge, and encumbered by his baggage and transport, having to accept battle on the march against an enemy three times as strong, who would hem him in from two sides.
Kutuzov chose this latter course.
The French, the spy reported, having crossed the Vienna bridge, were advancing by forced marches toward Znaim, which lay sixty-six miles off on the line of Kutuzov's retreat. If he reached Znaim before the French, there would be great hope of saving the army; to let the French forestall him at Znaim meant the exposure of his whole army to a disgrace such as that of Ulm, or to utter destruction. But to forestall the French with his whole army was impossible. The road for the French from Vienna to Znaim was shorter and better than the road for the Russians from Krems to Znaim.
The night he received the news, Kutuzov sent Bagration's vanguard, four thousand strong, to the right across the hills from the Krems-Znaim to the Vienna-Znaim road. Bagration was to make this march without resting, and to halt facing Vienna with Znaim to his rear, and if he succeeded in forestalling the French he was to delay them as long as possible. Kutuzov himself with all his transport took the road to Znaim.
War and Peace -by- Leo Tolstoy