Ernst von Rüchel (21 July 1754 – 14 January 1823) was a Prussian general who led an army corps in a crushing defeat by Napoleon at the Battle of Jena on 14 October 1806.

In 1806 during the Napoleonic Wars he held an important army command but has been criticized for his actions at Jena.

The other two armies were led by Charles William Ferdinand, Duke of Brunswick and Frederick Louis, Prince of Hohenlohe-Ingelfingen.

Rüchel's army was split between Eisenach and Gotha with Karl August, Grand Duke of Saxe-Weimar-Eisenach's division farther south at Schmalkalden and Johann Friedrich von Winning's detachment at Vacha.

They planned for Brunswick to move north toward Halle, while Hohenlohe covered his eastern flank by defending at Jena.

[10] On 14 October, Brunswick's army ran head on into Louis Davout's III Corps near Auerstedt and was badly defeated.

Just before his troops reached Kapellendorf around 1:00 PM, a courier brought news that the Prussian army was defeated.

It took Rüchel a total of four hours to move 12 kilometers, including the time it took to break camp; this was not a slow pace by Prussian standards.

[14] Christian Karl August Ludwig von Massenbach, Hohenlohe's chief of staff, directed Rüchel to move east from Kapellendorf.

At this moment, Marshal Joachim Murat directed the French Reserve Cavalry into the contest, with a division of cuirassiers in the lead.

[15] During the maneuvers that ended in the Battle of Eylau on 7 and 8 February 1807, Rüchel commanded the 4,000-strong Prussian garrison of Königsberg.