Battle of Jena–Auerstedt
The twin battles of Jena and Auerstedt (; older spelling: "Auerstädt") were fought on 14 October 1806 on the plateau west of the river Saale in today's Germany, between the forces of Napoleon I of France and Frederick William III of Prussia. The decisive defeat suffered by the Prussian Army subjugated the Kingdom of Prussia to the French Empire until the Sixth Coalition was formed in 1813.