To fill the breach left by Augereau's decimated corps, Napoleon ordered Murat's cavalry reserve, 80 squadrons of 10,700 cavalrymen, into action at 10:30 in the morning.
They had to cover 2,500 yards (2,300 m) of snow-covered, obstacle-filled ground, which they could not do at a gallop.
Murat's Reserve charged into the Russian squares in two columns: Grouchy's cavalry, d'Hautpoul's cuirassiers and General Louis Lepic's grenadiers—24 squadrons in total—were flank to flank when they hit the Russian center.
This was the occasion of Lepic's famous comment, "Heads up, by God!
those are bullets, not turds!"
Grouchy, Lepic, and d'Hautpoul's horse broke the center, wheeled, and charged a second time.
On the second charge, they broke the second formation of squares; at this point, Grouchy's men were forced back, but d'Hautpoul's cuirassiers pounded forward, reaching the Russian reserve.

At this point, the horses were nearly blown, but d'Hautpoul's cuirassiers charged the third line, which they also broke.
The Russian Cossacks, assembled in the reserve, entered the melee, but their light horses were no match for the French mounts, big horses confiscated from the Prussians the previous year.
The Russian infantry had started to reform their squares behind d'Hautpoul's men.
During this charge, d'Hautpoul was struck by artillery grapeshot and badly wounded.
Several of his men managed to carry or drag him back to French lines.

Napoleon's valet recounted:
... I seem still to hear the brave d'Hautpoul saying to His Majesty, just as he was galloping off to charge the enemy: "Sire, I am going to show you my big heels; they will go into the enemies' squares as if they were made of butter!"
An hour later he was dead.
One of his regiments while fighting in an interval of the Russian army, was shot down and cut to pieces by the Cossacks; only eighteen of them escaped.
General d'Hautpoul, three times forced to recoil with his division, thrice rallied them to the charge; the third time, he again rushed on the enemy, crying in a loud voice: "Cuirassiers, forward, in the name of God!
forward, my brave cuirassiers!"
But grapeshot had mowed down too many of these heroes.
Very few of them were in condition to follow their leader, who fell, covered with wounds, in the middle of a Russian square into which he had flung himself almost alone.

The Emperor ordered the best surgeons to attend to d'Hautpoul.
These disagreed on the method of treatment.
Against the advice of the military surgeon, Larrey, d'Hautpoul refused to have his leg amputated and he died a few days later.

There is some disagreement in the records about his actual date of death: the original death record of the parish at Eylau indicates he died of wounds on 1 February 1807, but this was before the battle, and it is possible that the pastor simply left off a digit in his record, or, more likely, that the record was transcribed incorrectly.
Other records suggest that he died the day after the battle (8 February), on 11 February, or on 14 February.
Originally buried at Worienen, His son, Alexandre Joseph Napoléon, brought his remains to France in 1840 to be buried in the family crypt at the Père Lachaise Cemetery in Paris.
 D'Hautpoul's heart is conserved in a vault in Les Invalides, and his name is inscribed on Column 16 of the Arc de Triomphe, among the first 384 names to be inscribed at the Arc.
To fill the breach left by Augereau's decimated corps, Napoleon ordered Murat's cavalry reserve, 80 squadrons of 10,700 cavalrymen, into action at 10:30 in the morning. They had to cover 2,500 yards (2,300 m) of snow-covered, obstacle-filled ground, which they could not do at a gallop. Murat's Reserve charged into the Russian squares in two columns: Grouchy's cavalry, d'Hautpoul's cuirassiers and General Louis Lepic's grenadiers—24 squadrons in total—were flank to flank when they hit the Russian center. This was the occasion of Lepic's famous comment, "Heads up, by God! those are bullets, not turds!" Grouchy, Lepic, and d'Hautpoul's horse broke the center, wheeled, and charged a second time. On the second charge, they broke the second formation of squares; at this point, Grouchy's men were forced back, but d'Hautpoul's cuirassiers pounded forward, reaching the Russian reserve.
At this point, the horses were nearly blown, but d'Hautpoul's cuirassiers charged the third line, which they also broke. The Russian Cossacks, assembled in the reserve, entered the melee, but their light horses were no match for the French mounts, big horses confiscated from the Prussians the previous year. The Russian infantry had started to reform their squares behind d'Hautpoul's men. During this charge, d'Hautpoul was struck by artillery grapeshot and badly wounded. Several of his men managed to carry or drag him back to French lines.
Napoleon's valet recounted:
... I seem still to hear the brave d'Hautpoul saying to His Majesty, just as he was galloping off to charge the enemy: "Sire, I am going to show you my big heels; they will go into the enemies' squares as if they were made of butter!" An hour later he was dead. One of his regiments while fighting in an interval of the Russian army, was shot down and cut to pieces by the Cossacks; only eighteen of them escaped. General d'Hautpoul, three times forced to recoil with his division, thrice rallied them to the charge; the third time, he again rushed on the enemy, crying in a loud voice: "Cuirassiers, forward, in the name of God! forward, my brave cuirassiers!" But grapeshot had mowed down too many of these heroes. Very few of them were in condition to follow their leader, who fell, covered with wounds, in the middle of a Russian square into which he had flung himself almost alone. 
The Emperor ordered the best surgeons to attend to d'Hautpoul. These disagreed on the method of treatment. Against the advice of the military surgeon, Larrey, d'Hautpoul refused to have his leg amputated and he died a few days later.
There is some disagreement in the records about his actual date of death: the original death record of the parish at Eylau indicates he died of wounds on 1 February 1807, but this was before the battle, and it is possible that the pastor simply left off a digit in his record, or, more likely, that the record was transcribed incorrectly. Other records suggest that he died the day after the battle (8 February), on 11 February, or on 14 February. Originally buried at Worienen, His son, Alexandre Joseph Napoléon, brought his remains to France in 1840 to be buried in the family crypt at the Père Lachaise Cemetery in Paris.  D'Hautpoul's heart is conserved in a vault in Les Invalides, and his name is inscribed on Column 16 of the Arc de Triomphe, among the first 384 names to be inscribed at the Arc.
Jean-Joseph Ange d'Hautpoul