A dreadful thunder-storm was the welcome which they received in this wild land; and shortly after the Emperor received intelligence that the Russians were falling back on every side, and manifested an evident intention to evacuate Lithuania without a battle. The Emperor urged forward his columns with even more than his usual promptitude, eager to strike one of those formidable blows by which he was wont to annihilate his enemy at the very commencement of the campaign. This gave rise to an event more ominous than the fall of his horse, or the tempest which received him on the banks of the Niemen. The river Wilia being swollen with rain, and the bridges destroyed, the Emperor, impatient of the obstacle, commanded a body of Polish cavalry to cross by swimming. They did not hesitate to dash into the river. But ere they reached the middle of the stream, the irresistible torrent broke their ranks, and they were swept down and lost almost to a man, before the eyes of Napoleon, to whom some of them in the last struggle turned their faces, exclaiming, "_Vive l'Empereur!_" The spectators were struck with horror.[116] But much greater would that feeling have been, could they have known that the fate of this handful of brave men was but an anticipation of that which impended over the hundreds of thousands, who, high in health and hope, were about to rush upon natural and artificial obstacles, no less formidable and no less insurmountable than the torrent which had swept away their unfortunate advanced guard. While his immense masses were traversing Lithuania, Napoleon fixed his headquarters at Wilna,[117] the ancient capital of that province, where he began to experience the first pressure of those difficulties which attended his gigantic undertaking. We must pause to detail them; for they tend to show the great mistake of those who have followed Napoleon himself in supposing, that the Russian expedition was a hopeful and well-conceived plan, which would certainly have proved successful, if not unexpectedly disconcerted by the burning of Moscow, and the severity of the weather, by which the French armies were compelled to retreat into Poland.