Jena, Battle of

In the Napoleonic Wars, comprehensive French victory over the combined Prussian and Saxon armies on 14 October 1806 at Jena, Germany, 90 km/56 mi southwest of Leipzig. Prussian and Saxon losses amounted to some 40,000 troops and 200 guns, while French casualties were 14,000. Napoleon so broke the Prussian forces that they were unable to prevent him marching on Berlin, and this disaster led to the complete overhaul and re‐organization of the Prussian Army which laid the foundations for its subsequent military prowess.

Austria had been seeking Prussia's aid in the fight against Napoleon for some time, but it was not until Napoleon was returning to France after Austerlitz that Prussia finally declared war. Napoleon acted promptly: his army was resting near Würzburg and he immediately marched north. The Prussian commander, the Duke of Brunswick, had begun moving south with 143,000 troops, and a separate force of 44,000 Prussians was moving south under Prince Hohenlohe. These two forces concentrated near Weimar and then moved separately, Brunswick heading for Naumberg and Hohenlohe for Jena. Napoleon split his army in two, placing Marshal Louis Davout with 27,000 troops near Auerstadt to intercept Brunswick and holding the rest of his army, consisting of about 56,000 troops, near Jena to deal with Hohenlohe. He then intended to swing north and deal with the Brunswick force which Davout would be holding in place. Neither of the Prussian forces was particularly well‐trained or experienced, and while Napoleon shattered Hohenlohe's army, Davout routed Brunswick's force.