Napoleon put an end to the millennium-old Holy Roman Empire in 1806, forming his own Confederation of the Rhine, and reshaped the political map of the German states, which were still divided. The wars, often fought in Germany and with Germans on both sides as in the Battle of the Nations at Leipzig, also marked the beginning of what was explicitly called "French–German hereditary enmity". Napoleon directly incorporated German-speaking areas such as the Rhineland and Hamburg into his First French Empire and treated the monarchs of the remaining German states as vassals. Modern German nationalism was born in opposition to French domination under Napoleon. In the recasting of the map of Europe after Napoleon's defeat, the German-speaking territories in the Rhineland adjoining France were put under the rule of Prussia.