The Congress of Vienna established an international system of reactionary governments dedicated to maintaining a set of European boundaries, preventing revolutions and changes in government, and stopping any one power from becoming too powerful. To this end, the Congress powers agreed to meet whenever trouble should crop up in Europe to discuss how to fix it.
The first meeting of the Congress System was in 1818, at the Congress of Aix-la-Chapelle. This meeting dealt with the coalition of European armies that had been occupying France since Napoleon's defeat. At Aix-la-Chapelle, the powers decided to withdraw their armies. Alexander I, always a champion of "collective security", suggested the idea of an international military force, made up of troops from all nations, that would be available to suppress revolutions wherever they appeared. The British foreign minister Viscount Castlereagh vehemently opposed the suggestion. Alexander I's suggestion was not adopted.
In 1820, as a reaction to the evident collapse of the government of Naples, Metternich called another meeting, the Congress of Troppau. Metternich wanted to stop the revolution in Naples from spreading. At Troppau, Metternich met with Alexander I and managed the formerly liberal Czar to adopt a more reactionary stance. The Czar, who had seen that liberal reforms in Poland had inevitably led his subjects to disagree with him, did not need much convincing. At Troppau, Austria, Prussia and Russia allied to restore the King of Naples. Britain, though anti-Revolutionary, did not want to be bound by continental commitments. Thus, Britain stayed out of intervention in Naples, as did France.
Despite the congresses, revolutionary hotspots continued to crop up. In the early 1820s the Bourbon government of Spain seemed especially fragile. At the same time, Greek nationalists sought more actively to establish a Greek nation in Turkey. To deal with these developments, Metternich called the Congress of Verona in 1822. The congress moved against the Greek revolutionaries, who really did not have the military power to take over Turkey at this time anyway. The Congress also allowed France to send an army into Spain to end the revolt and stabilize the Bourbon king. The revolution in Spain was quickly smashed.
The period of Metternich's congresses defined an era in which the governments in power attempted to create a reactionary international system. This system came to be called the Holy Alliance, appropriating the name of the coalition of Christian values Alexander had wanted to set up at the Congress of Vienna. The Holy Alliance was also called the Congress System, and in general the powers involved saw revolution and change as diseases. The reactionaries believed that if revolution cropped up in one part of Europe, it had to be destroyed, or else would spread like some epidemic.
Aix-la-Chapelle requires some explanation. First of all, why, only three years after Napoleon, did the European powers so easily agree to withdraw their forces from France? For one, they wanted the French to accept Louis XVIII, and if he was backed by foreign armies, it was almost certain that the population would hate him. Furthermore, French banks had paid off the French war debt (France now owed the debt to its bankers, not the other powers), so there was less reason for European armies (costly to maintain in the field) to remain stationed in France. Second, why did the British oppose an international "peacekeeping" force to put down revolutions throughout Europe? Were they pro-revolutionary? The answer is a resounding no. The Tory government in Britain was highly conservative. However, they wanted to be able to decide British intervention in military matters on a case-by-case basis. They did not want to commit forces to future events that might spiral out of control.