They raised to a high pitch the spirits of the Russian soldiery; and they afforded Napoleon such a specimen of the character of his new enemy, that instead of pursuing the campaign, as he had announced in his bulletins, he thought fit to retire, and place his troops in winter quarters.

He himself took up his residence at Warsaw, and the army occupied cantonments in various towns to the eastward.
But General Bennigsen, having proved at Pultusk what Russian troops could do when under a determined commander, no sooner found himself at the head of an army of nearly 100,000 men, than he resolved to disturb the French in their quarters, and at all events give them such occupation as might enable the King of Prussia to revictual Konigsberg, where the few troops, gathered round that unfortunate sovereign, were already beginning to suffer many privations.

With this view Bennigsen advanced as far as Mohrungen, where the French sustained considerable damage in a skirmish, and from whence his Cossacks spread themselves abroad over the country--creating such confusion, that the leaguer of Konigsberg being for the moment relaxed, the Prussian garrison received welcome supplies of all kinds, and Napoleon himself perceived the necessity of breaking up his cantonments, and once more concentrating the army for active war.
His design was to occupy Willensberg, to the rear of the great Russian camp at Mohrungen; thus cutting off the new enemy's communications with his own means of resource, in the same manner which had proved so fatal to the Austrians at Ulm, and the Prussians at Jena.

But Bennigsen, having learned the plan from an intercepted despatch, immediately countermarched his army with masterly skill, and thus involved Napoleon in a long series of manoeuvres, not to be executed in such a country at that dismal season without the extremity of hardship.

The Russians themselves, inured as they were to northern climates, and incapable of even dreaming that a soldier could seek safety in flight, were reduced to the border of frenzy by the privations of these long marches.