Jena-Auerstedt · 1806

The central blow of the War of the Fourth Coalition against Prussia and its Saxon ally. Berlin entered the war out of fear of French control over Germany and Napoleon's Confederation of the Rhine; on 14 October 1806 Hohenlohe's mixed Prussian–Saxon army was broken at Jena, and Brunswick's main Prussian force at Auerstedt. The double defeat destroyed the old Prussian army, opened the road to Berlin, and shifted the war into a Russo-French struggle in Poland.