temperatures reached dangerously hot and humid levels. The dampness and bitter cold of the night also played a significant role by providing little opportunity for rest. Progress of the battle Tactics Benningsen had been fooled into retreat by false reports of the French numbers. The Russians, having moved back to Heilsberg, had some protection from substantial fieldworks. In order to storm the fortifications, Napoleon had to choose between an immediate advance or a flanking movement, threatening the Russian supply base of Königsberg (now Kaliningrad). He chose the latter, and the French thus positioned themselves so as to cut off any opportunity for the Russians to obtain reinforcements. The battle The French cavalry under Joachim Murat was selected to lead the frontal attack, but Napoleon did not arrive on the field in person until Murat had already led a disastrous charge. Marshal Mortier and Marshal Davout advanced on the Königsberg side. Soult and Lannes, leading separate cavalry units, and Ney, with the infantry, moved forwards on both sides of the River Łyna. These smaller units proved ineffective, especially when Prussian reinforcements arrived, sent by Anton Wilhelm von L'Estocq at Bennigsen's request. Lannes made an unsuccessful attack which cost the French 3,000 casualties. On the Russian side, Bennigsen was suffering from fever and had difficulty remaining in command. On 11 June, the substantial casualties on both sides and the success of the Russian defence gave Bennigsen and Napoleon little choice but to call an undocumented truce to end hostilities. The French had lost an estimated 12,000 men. The truce was focused primarily on the recovery of wounded soldiers. The battle ended with medics and soldiers from both sides helping the wounded and retrieving the dead. When Napoleon entered the deserted Russian positions the following day, he found that all except the wounded had been evacuated overnight. Outcome and post-war analysis This battle is recognized as having been tactically inconclusive due to neither side having gained any significant ground, it is most notably discussed as a battle that yielded little change in the balance of strength between the Russians and the French. By most accounts, this was a successful Russo-Prussian rearguard action. Napoleon never realized he faced the entire army at Heilsberg. Murat and Soult attacked prematurely and at the strongest point in the Russo-Prussian line. The Russians had built extensive fortifications on the right bank of the Alle river, but only a