The Holy Roman Empire was a loose confederation of central European states that lasted from 962 until 1806. In general, the Empire was characterized by particularism and disunity. It consisted of more than three hundred states of varying size and importance, each sovereign, with its own army and regulations. The Empire was also composed of a diverse array of national groups, which included Danes, Dutch, Flemish, Belgians, Czechs, Swiss and Germans. It also included many religious groups, such as the French Huguenots and Swiss Mennonites, many of whom had come to the German lands after the Reformation to escape religious and ethnic persecution at home.
The Holy Roman Empire was formed in 962, when Otto I was crowned Holy Roman Emperor. It reached the height of its power under Henry II, who reigned from 1046 to 1056, and became centered on Germany.
The Hapsburg dynasty supplied nearly all of the Emperors from Albert II in 1439 up until 1806. However, in 1648, the Treaties of Westphalia, which concluded the Thirty Years' War, recognized the independence of the German princes. This destroyed the overwhelming power of the Holy Roman Emperors. After the war, the Holy Roman Empire was severely weakened. The German population decreased dramatically, numerous German cities were devastated, and German industry and commerce took over a century to regain their 16th century levels. The middle class declined and the towns were ruled by territorial princes, or their appointees, rather than by businessmen and merchants. The German princes became collectively stronger than the emperor and they had their own armies, courts, and coinage. Moreover, the German princes determined their own foreign policies and formed their own alliances with non-German states, even against Imperial interest. At this point, there were over two hundred German principalities that enjoyed such independence. Prussia emerged as the leading German state in the late 18th century under Frederick II. By that time, the Holy Roman Empire was little more than a name. It was formally ended in 1806, by Napoleon.