After Napoleon's first abdication in 1814, the powers that had defeated him met at Vienna in September of that year. Austria's chancellor Metternich was the host; the British foreign secretary Castlereagh brought diplomatic weight; Tsar Alexander I intervened personally; and France, though the defeated party, recovered a place at the table thanks to Talleyrand. Together they made the congress the inaugural scene of nineteenth-century diplomacy. The work was largely done behind closed doors; there was no formal plenary, and most decisions ripened in bilateral and trilateral talks.

The central aim was to weaken France enough to be safe but not enough to be vengeful, and to set up a balance in which no single power could dominate the continent. Belgium was joined to the Netherlands; Poland was partitioned once again, the bulk of it going to Russia as 'Congress Poland'; the German lands were reorganised as a loose Confederation of 39 states; Italy remained a 'geographical expression', much of it tied to Austria; Britain secured its overseas gains (Cape Colony, Malta, Ceylon). In March 1815 Napoleon's return from Elba forced the congress to test its decisions in war before the ink had dried; after Waterloo, the settlement was restored.

The system the congress created — later called the Concert of Europe — rested on the great powers' commitment to meet at regular intervals and resolve crises short of war. It is the first institutional sketch of modern great-power diplomacy; the genealogy of the League of Nations and the United Nations runs back here. Between 1815 and 1848 the system prevented a continent-wide war — measured against the Napoleonic years just past, no minor achievement.

The Vienna order was, however, fundamentally a restoration project. It put legitimate dynasties back on their thrones, treated nationalism and liberalism as threats, and made suppressing them a principle of government. In Poland, Italy, Germany, and Hungary, the demand for national unity was postponed by congress design for decades; the revolts of 1830, 1848, and eventually the national unifications of the 1860s (Italy, Germany) were the pressure of Vienna's settlement breaking through. Still, the framework Metternich helped build remained the basic grammar of European diplomacy until the First World War.