When Paul Schroeder called the Congress of Vienna agreement signed in 1815 the most successful peace treaty of all time, he did so with an eye to explaining the contours of the European great power system that evolved through the nineteenth century. In that system, as Schroeder explains, the political equilibrium between the great powers was maintained in order that no one power – be it Russia, France, Prussia, the Habsburg Empire or Great Britain – would dominate.
For Schroeder, the key to the ‘concert system’ or ‘Congress system’ (two terms that are largely interchangeable, although historians love to debate them) was more than a willingness to meet and discuss common concerns professed among the powers. It also reflected widespread acceptance that Europe’s crises should be stage-managed collectively. Hedley Bull described the inclination as a ‘custodial duty’ professed by the great power monarchies over the rest of Europe.