Three weeks after the passage of the Rhine, the Emperor wrote to Josephine: "I have destroyed the enemy merely by marches." It was literally true. On October ninth, the French, having beaten the parties sent out to harry them, had crossed the Danube also. Soult seized Memmingen and cut off the retreat to the Tyrol; Bernadotte and Davout remained to observe the Russians, whom they expected to see at any moment. In a sort of dazed uncertainty Mack finally marched out from Ulm to cross the Danube at Günzburg; but he found Ney in possession of the bridge, and in the night of the tenth he returned to the city. Two days were spent in discussions as to the probable course of the French, Mack persisting in the hallucination that they had retreated, the archduke, with better sense, perceiving that the toils were ever drawing closer about his army.
On the twelfth Napoleon moved with his whole force. The Archduke Ferdinand escaped into Bohemia with three battalions of infantry and eleven cavalry squadrons; but Mack, now stubbornly insisting that the Emperor was going to attack the Russians, remained, as he said, to strike the passing columns of the French on their flank! On the thirteenth it became clear that the goal of the enemy was Ulm; on the fourteenth they had virtually beset the town; and on the sixteenth the mortified commander opened negotiations for surrender, which were completed the following day. "If within a week," ran the stipulations, "the auxiliary forces do not appear, the army of Ulm are prisoners of war: except the officers, who march out on parole." On the (p.~367) eighteenth, Murat captured the division of Werneck at Nördlingen. In a personal interview between the Emperor and Mack on October twentieth, three days before the expiration of the limit, the latter was wheedled into admitting the terms as already complete, and twenty-three thousand Austrians laid down their arms. During the scene, according to the journal of one of Mack's officers, Napoleon, "in the uniform of a common soldier, with a gray coat singed on the elbows and tails, a slouch hat, without any badge of distinction, on his head, his arms crossed behind his back and warming himself at a camp-fire, conversed with vivacity and made himself agreeable." An Austrian corps had started from Vienna to guard the crossing of the Inn; the Archduke John was advancing from the Tyrol; the Archduke Charles was holding the Adige. A month later all these were able to unite at Marburg in Styria; but they were too few to assume the offensive, and Mack's capitulation at Ulm was the virtual destruction of Austria's power. The safety of Vienna depended not on its feeble garrison, but on the Russians, who had gathered on the Inn at Braunau and on the Enns at Wels. Almost immediately the French, who had been "gathered to strike," were "separated to live," as their commander's motto ran. Ten days later Braunau with all its stores fell into the hands of Lannes without a blow, and the van of the allies began a somewhat precipitate retreat toward the river Enns, the line which the Aulic Council at Vienna had determined to defend.