Although the Prussian army had seen only limited combat during the early Revolutionary Wars, its reputation up to the start of the 1806 campaign was based largely on its exploits during Frederick the Great's time. Not surprisingly, it was with some trepidation that the French set off to do battle with the highly vaunted Prussian cavalry, which still enjoyed the reputation based on a string of notable successes under Seydlitz during the previous era. During the previous year's campaign, the French military authorities had responded to the expected Russian cavalry threat by placing local cavalry reserves at the rear of divisional mixed order formations, whose flanks were protected by closed columns. Though sufficient against irregular Cossack cavalry, this would not guarantee complete safety against the quality of cavalry expected from the Prussians. There is some evidence that the French military remembered its Egyptian campaigns. The dense formations of the latter would be impractical against the Prussians, who unlike the Mamelukes and Turks could be counted on to use their artillery with deadly effect.
The French came up with a number of solutions to this dilemma. At Jena, Suchet's division was initially deployed as a large divisional square. The 17th Légère formed the front face, and Videl's brigade the rear. Both were deployed in line. The two flank sides were formed by the 34th and 40th Regiments, both in closed columns. Thirteen miles away at Auerstadt, Gudin and Morand's divisions had to endure large-scale attacks delivered by the Prussian cavalry. On the right, Gudin's force met a series of impetuous charges delivered by the veteran Blücher. The 25th and 12th Regiments, as well as a battalion of the 21st, bore the brunt of these assaults in battalion and regimental squares. The other battalion from the 21st remained in line to connect this flank with the French forces in Hassenhausen. Interestingly, the three squares were placed obliquely to one another to maximize the effect of cross-fire.
Morand's response to another cavalry threat later that morning is even more illustrative. His division, initially advancing in closed columns, deployed in battalion lines and then, when faced with the enemy cavalry, maneuvered into two rows of battalion squares. These were positioned to form the carrés oblique, rehearsed so frequently by the 33rd Regiment in 1801. Lest it be thought this arrangement was fortuitous, Gneisenau's observations on the effect of these precautions on Blücher's efforts should be considered. Writing his biography of the Marshal, Gneisenau attributed the failure of the Prussian cavalry on Gudin's right to the potency of the new French formations more than any other factor:
His [Blücher's] old maneuvers, of indirect charges following each other in succession, and skirmishing on all sides, first throwing the files into disorder, and then, by a heavy unexpected charge, to break through, were here found of no avail. The new tactics of Napoleon, of drawing up his infantry in alternate squares, flanked by light artillery, and connected by troops in line, frustrated all Blücher's desperate attempts to make an impression. He felt himself foiled. On making his last charge he had his horse killed under him. He then drew back his cavalry in good order towards Eckartsburg, and passed through Auerstadt.