The Congress of Vienna sought to restore the pre-1789 European order—legitimate monarchies, aristocratic privilege, and a balance of power that would prevent another revolutionary upheaval like the French Revolution or Napoleonic Wars. Its toolkit:
Bourbons returned to France (Louis XVIII), Spain, and Naples; Braganças to Portugal; Orange-Nassau to the Netherlands; Pope to Papal States; German princes to their thrones. The principle: the rightful ruler is the one who held the throne before 1789.
Russia, Prussia, Austria (later France, UK) pledged to intervene against revolutionary movements. The Holy Alliance (Alexander I's brainchild) framed this as a Christian duty; the Quadruple/Quintuple Alliance made it a diplomatic mechanism. Result: interventions in Naples (1821), Spain (1823), suppression of 1830/1848 revolts.
No single state should dominate. France contained but not crippled (Talleyrand's diplomacy). Britain as offshore balancer. Russia and Austria as conservative eastern anchors. Prussia as intermediate power.
Carlsbad Decrees (1819) censored press, universities, and banned nationalist student fraternities (Burschenschaften) in German states. Metternich's system made "legitimacy" synonymous with repression.
Short term: yes—no general European war for 99 years (1815–1914). Long term: no. Nationalism, liberalism, and industrial change proved uncontainable. 1830, 1848, Italian/German unification, and WWI all stemmed from forces Vienna tried to freeze.
Legacy: A masterclass in diplomatic engineering that bought a century of relative peace but mistook a pause for a permanent settlement.