The Prussian King understood well, on learning the fall of Naumburg, the imminent danger of his position; and his army was forthwith set in motion, in two great masses; the former, where he was in person present, advancing towards Naumburg; the latter attempting, in like manner, to force their passage through the French line in the neighbourhood of Jena. The King's march was arrested at Auerstadt by Davoust, who, after a severely contested action, at length repelled the assailant. Napoleon himself, meanwhile, was engaged with the other great body of the Prussians. Arriving on the evening of the 13th October at Jena, he perceived that the enemy were ready to attempt the advance next morning, while his own heavy train were still six-and-thirty hours' march in his rear. Not discouraged with this adverse circumstance, the Emperor laboured all night in directing and encouraging his soldiery to cut a road through the rocks, and draw up by that means such light guns as he had at command to a position, on a lofty plateau in front of Jena, where no man could have expected beforehand that any artillery whatever should be planted, and where, accordingly, the effect even of a small park proved more decisive than that of a much larger one might have been under other circumstances. Buonaparte spent all the night among the men, offering large sums of gold for every piece that should be dragged to the position, and continually reminding his followers that the Prussians were about to fight not for honour, but for safety,--that they were already isolated as completely as Mack's army had been at Ulm, and on stern resistance must needs submit to the fate of the Austrians. Lannes commanded the centre; Augereau the right; Soult the left; and Murat the reserve and cavalry.