How did the Congress of Vienna ensure peace in Europe?

The Congress of Vienna wanted to ensure peace in Europe by resolving issues which had remained after the French Revolution and the Napoleonic Wars. To do this, the council of European ambassadors wanted to restore old European boundaries and monarchies before Napoleon's rule and wanted to re-size European powers so that they could balance each other and remain at peace. However, although all the powers gained territory, they did not all gain the same amount.