The final conflict that led to the unification of Germany was the Franco-Prussian War, which took place in 1870-1871. The war ended with a decisive victory for Prussia, a state in northern Germany, and the subsequent unification of Germany under Prussian leadership. The main cause of the war was a dispute between the French Emperor Napoleon III and the Prussian Chancellor Otto von Bismarck over the candidacy of a Hohenzollern prince for the vacant throne of Spain. The conflict quickly escalated into a full-scale war, which ended with the defeat of France and the establishment of the German Empire.