The Battle of Sedan was fought September 1, 1870, during the Franco-Prussian War (1870-1871). Battle of Sedan, (Sept. 1, 1870), decisive defeat of the French army in the Franco-German War, causing the surrender of Napoleon III and the fall of the Bonaparte dynasty and the Second French Empire; it was fought at the French border fortress of Sedan on the Meuse River, between 120,000 French troops under Marshal Mac-Mahon and more than 200,000 German troops under General Helmuth von Moltke.
Until 1651, the Principality of Sedan belonged to the La Tour d'Auvergne family. With help from the Holy Roman Empire, it defeated France at the Battle of La Marfée. Their representative, Marshal Turenne, was born at Sedan on 11 September 1611. It was at that time a sovereign principality.
Moving to lift this siege, Marshal Patrice de MacMahon's Army of Châlons, accompanied by Emperor Napoleon III, engaged the enemy at Beaumont on August 30, but suffered a setback. With the beginning of the conflict, Prussian forces won several quick victories and besieged Metz.