In excuse for this action it has been urged that he had but two days' supply of bread in the camp, and that a forward move of Davoust's corps round his right flank threatened to cut him off from his base of supplies, Koenigsberg.[130] The first excuse only exposes him to greater censure.

The Russian habit at that time usually was to live almost from hand to mouth; but that a carefully-prepared position like that of Heilsberg should be left without adequate supplies is unpardonable.

On the two next days the rival hosts marched northward, the one to seize, the other to save, Koenigsberg.

They were separated by the winding vale of the Alle.
But the course of this river favoured Napoleon as much as it hindered Bennigsen.

The Alle below Heilsberg makes a deep bend towards the north-east, then northwards again towards Friedland, where it comes within forty miles of Koenigsberg, but in its lower course flows north-east until it joins the Pregel.
An army marching from Heilsberg to the old Prussian capital by the right bank would therefore easily be outstripped by one that could follow the chord of the arc instead of the irregular arc itself.
Napoleon was in this fortunate position, while the Russians plodded amid heavy rains over the semicircular route further to the east.
Their mistake in abandoning Heilsberg was now obvious.