When Napoleon was defeated in 1815 European leaders met at the Congress of Vienna to bring peace and bring stability back to Europe. Metternich and other delegates disliked democracy, it made them fear the idea of the French Revolutions. Wanted to change Europe back before Napoleon.
One goal was to prevent future French aggression. It was done by taking all lands by France, It made Nations around France stronger.
One goal was to maintain a balance of power in Europe. This was done by forming the concert of Europe. To maintain peace and stop revolutions. The decision helped maintain peace in Europe for almost 40 years.