Read the given passage and answer the following question.

Following the defeat of Napoleon in 1815, the European government was driven by a spirit of conservatism. Conservatives believed that established, traditional institutions of state and society – like the monarchy, the Church, social hierarchies, property, and the family –should be preserved. Most conservatives, however, did not propose a return to the society of pre-revolutionary days. Rather, they realized, from the changes initiated by Napoleon, that modernization could strengthen traditional institutions like the monarchy. It could make state power more effective and stronger. A modern army, an efficient bureaucracy, a dynamic economy, and the abolition of feudalism and serfdom could strengthen the autocratic monarchies of Europe. In 1815, representatives of the European powers who had collectively defeated Napoleon, met in Vienna to draw up a settlement for Europe. The congress was hosted by the Austrian Chancellor Duke Metternich. The delegates drew up the Treaty of Vienna of 1815 with the object of undoing most of the changes that had come about in Europe during the Napoleonic wars. The Bourbon dynasty, which had been deposed during the French Revolution, was restored to power and France lost the territories it had annexed under Napoleon. A series of states were set up within the boundaries of France to prevent French expansion in the future.

What was the purpose of the Congress of Vienna in 1815?