The Congress of Vienna was a historical event that took place in 1815. It was a meeting of European leaders to re-establish peace and stability after the Napoleonic Wars. During the Congress, several agreements were made, but one of the most important was the Treaty of Vienna.

The Treaty of Vienna was signed on June 9, 1815, by representatives of the major European powers. The agreement aimed to restore the balance of power in Europe by making territorial changes and establishing a network of alliances. The treaty also aimed to prevent the resurgence of French aggression, which had been prevalent during the Napoleonic Wars.

The treaty recognized the sovereignty of individual states, and their right to self-determination. It also recognized the importance of maintaining a balance of power in Europe, and established a system of alliances to deter future aggression. The treaty also agreed to the redistribution of territories that had been captured by France during the Napoleonic Wars.

The Treaty of Vienna was a major achievement in European diplomacy, as it not only restored peace and stability to the continent, but also created a framework for future cooperation between European nations. It also laid the foundation for the Concert of Europe, which was a system of international relations that aimed to prevent major wars in Europe.

In conclusion, the Treaty of Vienna was the most important agreement that came out of the Congress of Vienna. It laid the foundation for a new era of European diplomacy and established a framework for future cooperation between European nations. The treaty is a testament to the power of diplomacy and the importance of international relations in maintaining peace and stability in the world.