The German Confederation was formed following the Congress of Vienna in 1815, originally comprising 34 states of the former Holy Roman Empire, with a further five joining in 1820. After the turmoil of the French Revolution and the defeat of Napoleon, aristocratic leaders of the various states of Germany saw unity under a single Confederation, led by Austria, as a way of combating the spread of popular revolution whilst satisfying the growing desire for German unity. The two largest and most powerful kingdoms, Austria and Prussia, both extended outside the Confederation and recognized full integration as a threat to their dominance. In 1848 a revolution in Austria ousted state Chancellor, Prince Metternich, and forced promises of a new Imperial Constitution, which eventually fell through along with subsequent attempts to foment revolution. Amidst economic expansion Austria and Prussia’s rivalry continued to grow until war erupted and the Confederation dissolved in 1866.