A battle fought on the River Meuse, near the Belgian frontier, between French and Prussian forces during the Franco-Prussian War. The Prussians, discovering that MacMahon’s army had set out to relieve Metz, diverted two armies marching on Paris and encircled the army of Napoleon III at Sedan. The French, under heavy shellfire, surrendered unconditionally. Napoleon III was taken prisoner, together with a large army. In World War II the Germans breached the Maginot Line when they crossed the River Meuse at Sedan (1940).