The unification took place on January 18, 1871. After the Franco-Prussian War, the German princes proclaimed the German nation in Versailles, France, at the Hall of Mirrors. The unification joined together many independent German states, which became the German Empire. OTTO von Bismarck, Prime Minister of Prussia, became Chancellor of the Empire.The unification of Germany had begun many years earlier, during the Napoleonic Wars. At the Battle of Leipzig in 1813, which is also called the Battle of Nations, many of the German states joined Russia, Sweden and AUSTRIA to DEFEAT Napoleon's army. In 1815, the Congress of Vienna ended the Napoleonic Wars. Austria remained the most politically-powerful German STATE. Prussia emerged as Austria's political and diplomatic rival.There were many problems in unifying the German states. Not all POLITICIANS wanted unification. Some feared that it would give Austria and Prussia too much power among the many states. There were also problems in deciding who would collect taxes and how much was be paid.