19th-Century Codification and the Hague System

The Congress of Vienna, convened from September 1814 to June 1815 under the guidance of Austrian foreign minister Klemens von Metternich, redrew the political map of Europe after the defeat of Napoleon and established a set of diplomatic principles—legitimacy, restoration of pre-revolutionary dynasties where feasible, and a deliberate balance among the great powers—intended to prevent a recurrence of continent-wide war. Its Final Act also produced early multilateral achievements of lasting legal significance, including the first international agreement condemning the transatlantic slave trade and a codified set of rules on diplomatic precedence and the ranking of diplomatic agents, still substantially reflected in the modern law of diplomatic relations. The Congress gave rise to the Concert of Europe, an informal but sustained practice of periodic great-power conferences—at Aix-la-Chapelle (1818), Troppau (1820), Laibach (1821), and Verona (1822)—through which the major powers coordinated responses to revolutionary movements and territorial disputes, representing an early, if elitist and unevenly applied, experiment in collective diplomatic management of international order.