The trigger for war was a diplomatic row over the Spanish succession. Provoked by Bismarck, the Prussian chancellor, France declared war, which Bismarck countered with an alliance of the German states. Mobilizing at a speed that confounded the French, the German alliance achieved a string of victories in the Rhineland, forcing the main French army to take refuge in Metz (surrendering in October). A relief army, accompanied by the Emperor Napoleon III, was encircled at Sedan, in the Ardennes, and forced to surrender: the Emperor was taken captive. The German armies then converged on Paris. The siege of Paris spanned September 1870–January 1871. A Government of National Resistance was formed, and the remaining French forces were rallied, and repeatedly confronted the Germans, even managing a victory at Coulmiers. Ultimately, facing starvation, Paris surrendered. By the subsequent Treaty of Frankfurt, France ceded Alsace and northern Lorraine to Germany.
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