In the years following 1815, the four great powers, Britain, Russia, Austria and Prussia, agreed to hold periodic conferences to discuss matters affecting the Vienna Settlement 1814-1815, and to discuss the maintenance of order in Europe which was destroyed by the Napoleon Wars which lasted for over 20 years. In the year 1789, the French revolution broke out, a series of revolutionary wars began, leading to the rise of Napoleon Bonaparte. By 1808, Napoleon had gained control of almost all of Europe. During his reign, the reforms he carried out weakened the old absolute monarchies and helped to spread the powerful forces of liberalism and nationalism.

However, because of his conquests, the Balance of Power in Europe was destroyed. After the defeat of Napoleon in the Battle of Waterloo 1814, the great allied powers Britain, Russia, Austria and Prussia faced the problem of re-organising Europe. Therefore, they met in 1814-1815 at the Congress of Vienna, drawing up a settlement, which they hope to prevent one power from becoming too powerful in the future, and which would maintain peace. This settlement was the first attempt to establish a general peace in Europe by co-operation between the major powers. The idea of collective security called "Concert of Europe" was also developed. It suggested the great European powers co-operate to safeguard the stability and peace of Europe.

This can be done by settling disputes by active diplomacy and discussions. This arrangement became known as The Congress System, because the powers worked through international congresses and also putting the ideas of the Concert of Europe into practise. There are four major congresses held. They are: Congress of Aix-la-Chapelle 1818, where France was admitted to the Quintuple Alliance Congress of Trop peau 1820, which was a response to revolts in Spain, Portugal, Piedmont and Naples Congress of Laibach 1821, where Austria and Russia were ready to send soldiers against Italian revolts. Congress of Verona 1822, when French troops were used against rebellion in Spain and which Britain withdrew from the Quintuple Alliance afterwards After the above congresses held in the period 1818-1822, the Congress System finally ended, mostly because of the disagreement between the Allies.

With the collapse of this system, the powers then carried out their own policies independently. To conclude, we can assess the Congress System with three points. Firstly, it was short-lived and only an informal system. However, it set up a good tradition of using international conferences to settle disputes. Therefore it represented the first attempt to promote international co-operation. Most importantly, the rivalries also made a "balance of power" between the great powers possible.

There was relative peace and stability in Europe until the First World War in 1914.