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 result of the war was the secession of the France regions of Alsace and Lorraine to Prussia. This in turn led to a simmering resentment of Germany in France which in turn contributed to French public support for World War One as a means to win back the lands ceded to Germany.