The diplomatic “congress” was of course not invented during the nineteenth century—he Peace of Westphalia remained a historical reference throughout the period—however the diplomacy of that century was modern in that it developed various forms of multilateral diplomacy. At first sight, the chronology of congresses (diplomatic meetings where the major powers were represented by at least their Minister of Foreign Affairs) seems unbalanced: the time of the Holy Alliance saw the succession of the Congresses of Vienna, Aix-la-Chapelle (1818), Troppau (1820), Laybach (1821) and Verona (1822). A summit of major scope did not take place until 1856 in Paris, and then in 1878 in Berlin. However, this chronological imbalance is misleading, for it does not take into account the fluctuating but non-negligeable realities of “the Concert of Europe,” an international system that characterized the century between the fall of Napoleon and the start of The Great War.
The Europe of congresses was born from the last coalitions against Napoleon. The Congress of Châtillon opened on February 5, 1814, bringing together the plenipotentiaries of Russia, Austria, Prussia, and England. After the victory of the Allies and the Restoration in France, the Congress of Vienna took place from September 1814 to June 1815. The Alliance henceforth intended to guarantee the two constituent principles of the new Europe: the legitimacy of monarchy and the European balance of power, while fortifying against any revolutionary impulses, whether from France or elsewhere. In this spirit, Czar Alexander conceived the treaty of the Holy Alliance in September 1815, which Metternich and many others neither believed nor considered to be important. The foundation of the Europe of congresses was to a greater extent the Quadruple Alliance, which was established during the second Treaty of Paris (November 20, 1815) by those who defeated Napoleon. Article 6 of the treaty provided for the “occurrence at determined times” of meetings between sovereigns or their ministers, “dedicated to the major common interests and to the examination of measures that, in each of these periods, would be deemed the most beneficial for the rest and prosperity of the peoples, and for the keeping of the peace in Europe.”
The Congress of Aix-la-Chapelle gave its blessing to France's entry in the alliance of powers. The five “great powers,” finally complete, were supposed to form a kind of “Directory of Europe” tasked with maintaining the status quo. At Troppau and Laybach, Austria asked to be given the task of intervening alone against the revolution of Naples. The Congress of Verona entrusted France with a similar mission against the Spanish liberals. In reality, however, there was no consensus between the major powers, England being hostile on principle to armed intervention in the affairs of an independent country. For this reason, the “Directory of Europe” did not survive the Greek question, which would be resolved by a more restricted concert, with England, Russia, and France. “In early 1826, the Quintuple Alliance no longer existed,” acknowledged Metternich. “For the public, it still survived under the nickname of the Holy Alliance, and as such it was exposed to the disdain of the people by the leaders of the revolutionary party.”
A new phase thus began; as the historian Charles Dupuis wrote, “the experience had shown the advantages and conditions of agreement. Although the Concert of Europe could not aim to govern Europe, it could aspire to preventing, limiting, or settling certain European crises. It was in this more modest form—more intermittently and with narrower horizons—that a new career would open up for its benevolent action.”
After the Greek question, that of Belgium erupted in August 1830, with a European conference on the Belgian affair opening in London on November 4. The location itself was significant, as the English conception of the Concert of Europe imposed itself. The principle of non-intervention prevailed, for lacking this means of action, one had to renounce the status quo and learn to negotiate. For Palmerston, by accepting to compromise on the Belgian question in order to maintain peace, the negotiators “behaved as though they constituted a European cabinet.” The Directory transformed into a Concert, which was less ambitious and less rigid, but more flexible and effective.
During the Eastern Crisis of 1840, the fate of the Ottoman Empire was at stake, and the European balance of power and overall peace under threat. France found itself isolated from the coalition of the four other major powers, and had to give in, as isolation would condemn it to exclusion from the Concert of Europe, an unbearable situation from its point of view. The London Straits Convention of July 1841 concluded the affair.
In a certain way, a similar process was sketched out when Russia sought to extend its hegemony over the Ottoman Empire in 1853. France and England allied themselves and sought to form a coalition with Austria and Prussia. It was not a complete success, however, and the Crimean War could not be avoided. After Russia's defeat, the Congress of Paris took place from February to April 1856.
The Congress of Paris, which was long neglected but is better known today, appears as the genuine height of the diplomacy of the “Concert of Europe.” Not only did diplomats perfect the procedures for multilateral negotiations, but they also organized their expansion: on the political level, notably by providing for the Romanian principalities to be determined by a European Commission after consultation with the populations; and on the technical level, by making collective decisions in maritime law, and by promoting international conferences (on telegraphy, sanitary matters, navigation on the Danube and, later on, monetary problems). From conference to conference, an international legal and diplomatic life was successfully developed on the boundaries of politics, in essentially technical areas: this rise of international law and the emergence of an “international community” continued even during the time of nationalism.
In the wake of the Congress of Paris, it was possible to believe that the Concert of Europe was able to defuse international crises. Such was the case when the crises of Neuchâtel and Montenegro broke out, and later those of Lebanon and Crete. During each of these crises, a conference of ambassadors from the major powers met, and a conflagration was avoided.
Although the Concert of Europe worked for Eastern affairs—and this was still the case during the Congress of Berlin in 1878—the transformations of Western Europe took place outside of the Concert of Europe. This was the case for Italy in 1859, 1860 and again in 1867, Poland in 1863, Denmark in 1864, Germany in 1866 and 1870: each time a Congress was planned, but war prevailed over diplomacy, with the exception of the Luxembourg Crisis in 1867.
The Concert of Europe was consequently unable to peacefully manage the movement of nationalities in Europe. After 1870, it suffered from the constitution of rigid systems of diplomatic alliance. It nevertheless remained a reality for Eastern questions—in addition to the Congress of Berlin of 1878, there were numerous diplomatic conferences on the Balkans up until that of London in 1913—as well as for non-European matters: its last major moment was the Algeciras Conference in 1906, which also marked a new century through the new role of the United States.