German Confederation, 1815–66, union of German states provided for at the Congress of Vienna to replace the old Holy Roman Empire, which had been destroyed during the French Revolutionary and Napoleonic Wars. It comprised 39 states in all, 35 monarchies and 4 free cities. Its purpose was to guarantee the external and internal peace of Germany and the independence of the member states. In case of attack the members pledged mutual aid. Certain princes, however, were exempt from this provision. These were the king of England, as king of Hanover; the king of the Netherlands, as duke of Luxembourg; and the King of Denmark, as duke of Holstein and Lauenburg. As it was constituted, the confederation was little more than a loose union for mutual defense. Its main organ, a central diet that met at Frankfurt under the presidency of Austria, functioned as a diplomatic conference. Unanimity or a two-thirds majority was required for most decisions, and, in voting, the delegates were bound to instructions from their respective governments. The diet thus was ineffective. The strong reactionary influence of the Austrian statesman Metternich, backed by Prussia, dominated the confederation until 1848, when the liberal revolutions that swept Germany resulted in the creation of the Frankfurt Parliament. The diet was resumed in 1850. By the treaty agreed upon at Olmütz (Olomouc), Austrian leadership was temporarily restored, but the Austro-Prussian War (1866) led to the dissolution of the confederation and the establishment of the North German Confederation under Prussian leadership.