(Miłomłyn), leaving Mohrungen to be occupied by Bennigsen's troops. Markov followed up the French toward Liebemühl, while Baggovut's left advance guard seized Allenstein (Olsztyn). At Mohrungen on the 28th, Bennigsen called a halt to operations so that his tired troops could rest. Bernadotte continued withdrawing to the south until he reached Löbau (Lubawa) where he joined General of Division Jean-Joseph Ange d'Hautpoul's 2nd Cuirassier Division. This gave him 17,000 infantry and over 5,000 cavalry. The 4,500-man Prussian garrison of Graudenz (Grudziądz), under General of Infantry Wilhelm René de l'Homme de Courbière, had been besieged by General of Division Marie François Rouyer and a force of Hessians. At L'Estocq's approach, Rouyer raised the siege, allowing the Prussians to restock the garrison's food supplies on 31 January. This timely intervention allowed the garrison to resist the enemy besiegers until the end of the war. A Russian advance guard under General Pyotr Bagration linked L'Estocq and Bennigsen's main force, which was centered on Mohrungen, facing south. Pleased with his success so far, and expecting Napoleon to retreat to the west bank of the Vistula, Bennigsen was in for a surprise. Far from retreating, the French emperor launched a dangerous counterattack on 1 February. Napoleon saw that Bennigsen had advanced so far west that there was an opportunity to hit the Russian army in the left flank and rear. He ordered Bernadotte to continue retreating to tempt Bennigsen to move westward into the trap. Lannes with the V Corps and General of Division Nicolas Léonard Beker's dragoon division would keep an eye on Ivan Essen's detached force to the northeast of Warsaw. (These forces clashed in the Battle of Ostrołęka on 16 February.) Napoleon ordered the corps of Davout, Soult, Augereau, Murat, and the Imperial Guard northward to Allenstein, while Ney covered the gap between the main body and Bernadotte. On 1 February, the Russian commander enjoyed a great stroke of good luck. The orders to Bernadotte were given to an officer fresh from the military academy. This hapless individual, ignorant of the area, rode straight into a band of cossacks and was unable to destroy his dispatch. Soon, Bagration came into possession of the important document, which he forwarded to his army commander. As soon as he received the news, Bennigsen ordered the army to rapidly retreat on Jonkowo. As it happened, seven other couriers also fell into the hands of the cossacks,