(1820) Meeting of the Holy Alliance powers held at Troppau in Silesia (modern Opava, Czech Rep.).
Attended by representatives of Austria, Russia, and Prussia and by observers from Britain and France, the alliance signed a declaration of intention (the Troppau protocol) to take collective action against revolution. The congress agreed that states having undergone revolutions would be excluded from the European alliance. They invited the king of the Two Sicilies to meet at the Congress of Laibach to discuss intervention against the revolution in Naples. Britain and France did not accept the protocol, demonstrating the division between the eastern and western members of the alliance and seriously weakening it.