A loose alliance of European powers pledged to uphold the
principles of the Christian religion. It was proclaimed at the Congress of Vienna (1815) by the emperors of Austria and Russia, and the king of Prussia. All other European leaders were invited to join, except the pope and the Ottoman sultan. The restored French king Louis XVIII did so, as did most others; Britain did not. As a diplomatic instrument it was short-lived and never effective and it became associated with repressive and autocratic regimes.