The Franco-Prussian War of 1870-1871 (also called Franco-German war or 1870 war) was the result of Otto von Bismarck's plan to unify Germany. It was fought by the North German Federation (led by Prussia), and the southern German states of Baden, Wuerttemberg, and Bavaria against France under emperor Napoleon III. It involved a winter-time siege of Paris and ended with the Treaty of Frankfurt.
The main results of the war was the rise of a unified Germany as the dominant continental European power and the secession of the German-speaking French provinces of Alsace and Lorraine to the German Empire. This in turn led to a simmering resentment of Germany in France for regime change which in turn contributed to French public support for World War One as a means to win back the lands ceded to Germany and reclaim France traditional role as a dominant power.