Very interesting account!

I also find something from Crisis in the Snows, p. 283-284:

At the Battle of Jena, the Chasseurs a cheval had seen their colonel beheaded by a Prussian cannon ball. Their new leader. Colonel Bertrand Castex, possessed many of a light cavalry leader's requisite attributes; a superb seat, deadly thrust in a duel, and a blind eye toward looting. Having risen steadily from the ranks and served as the regiment's major, Castex had acquired great experience. But he had never before led a regiment in battle. On the snow covered slopes northwest of Windmill Hill, Castex observed the Russians struggling over the marshy lowlands and up the incline. He decided to try a tactical experiment to exploit the dragoons' lack of impetus by ordering his troopers to brandish their carbines and repel the charge with fire alone. According to Charles Parquin, who was present with the regiment, the French held their fire until the dragoons closed to within six yards: "the effect of the volley was terrible. Almost the whole of the enemy front rank was struck down. The enemy hesitated a moment; but soon the dead and wounded were replaced by the second rank, and a melee developed."25 Castex had been fortunate because mounted carbine fire was notoriously inaccurate and typically did little to arrest a line of charging cavalry Now he gambled again. Instead of counter-charging the wavering dragoons, Castex had his troopers receive the Russians at a standstill. This decision violated all principles regarding cavalry in battle and the 20th Chasseurs a cheval paid a stiff price for their colonel's unorthodox tactics. During the ensuing melee more than one hundred chasseurs were struck by Russian swords. The regiment's elite company lost twenty-seven out of one hundred troopers wounded or killed.
It could have been worse. While the dragoons occupied the chasseurs from the front, a band of cossacks tried to envelop the French left flank. An alert captain ordered the flank squadron to change front toward the cossack menace, and his initiative saved his regiment. Meanwhile, on the opposite flank, an infantry square poured musketry into the Russians whenever they had a clear field of fire. After suffering heavy losses the Russian dragoons retreated. Meanwhile, Foch's infantry found themselves confronting a much larger French force. Undaunted, Foch led them forward in a spirited bayonet charge. It failed to drive the French infantry from Windmill Hill and Foch retreated.
25. Parquin, Souvenirs du Commandant Parquin, 95. Parquin says that this action occurred at around 2 p.m. but this assertion does not jibe with Russian accounts