Beginning in January 1798, Revolutionary France under Napoleon Bonaparte (1769-1821) had invaded the left bank of the Rhine and into the Holy Roman Empire, merely a section of conflict that has become known as the Napoleonic Wars, in which France became the dominant continental European power, either directly or indirectly controlling Spain, The Netherlands, and sections of what is currently Italy and Germany. In 1803, after Great Britain had declared war on France, Napoleon invaded Central Europe (Germany) including the city of Hanover in Saxony, a possession of King George III of England. In 1806, while dismantling the remnants of the Holy Roman Empire, he created created the Duchy of Warsaw and partitioned Prussia. By introducing the Continental System throughout most of Europe, he demolished the long-standing city-states and small regional governments while strengthening the central government. The strong feeling of nationalism that was put into practice in the early 1800's led to the creation of the German nation in the latter 1800's.