German unification was formally achieved on 18 January 1871 when Wilhelm became Emperor of Germany in the Hall of Mirrors at Versailles after Prussia's victory in the Franco-Prussian War. However, the process of uniting the German-speaking populations had occurred gradually over the previous century through experimentation and the creation of organizations like the Prussian Zollverein customs union. While unification united many states, it also exposed religious, linguistic, social and cultural differences between inhabitants, showing that 1871 was just one point in the ongoing process of German unification.