With his customary inventiveness, Napoléon sees an…
January 1807 CE
He instructs Bernadotte to withdraw before Bennigsen's forces, and orders the balance of the Grande Armée to strike northward.
This maneuver might envelop the Russian army's left flank and cut off its retreat to the east.
By a stroke of luck, a band of Cossacks captures a messenger carrying Napoleon's plans to Bernadotte and quickly forwarded the information to General Pyotr Bagration.
At once Bernadotte is left unawares and a forewarned Bennigsen immediately orders a retreat east to Jonkowo to avoid the trap.
The Russians withdraw towards Allenstein, and later to Eylau.