The Treaty of Versailles, signed in 1919, formally ended the hostilities of World War One. The victorious nations of France, Britain, the United States, Italy, and Japan imposed harsh terms on the defeated Central Powers of Germany and Austria-Hungary. The Austro-Hungarian Empire was formally dissolved, and Germany was forced to make excessive reparation payments to the Allied powers. One of the clauses of the treaty was that the territory of Alsace-Lorraine, occupied by German forces, should be returned to French control.

The Kellogg-Briand Pact was signed in 1928 by most of the major powers in the world. It formally renounced war as a means of settling international disputes. Obviously, given that the Second World War broke out just a decade later, it was not effective; however, the principal it established was influential in the formation of the United Nations following the end of World War Two.

The Peace of Augsburg was signed in 1555. It ended the protracted Civil War that had been raging in the German Prince-led states of the Holy Roman Empire between the Lutherans and the Catholics. The Peace of Augsburg may be understood as an early extension of religious tolerance in Europe based on pragmatism; however, the extension of its tolerance had very strict limits. Firstly, the population of each princely state had little say in the religion its members could practice; that was decided by the ruler, and the rest of the population was then required to follow him. Secondly, all other Protestant denominations were excluded from the Peace of Augsburg—it only extended to Lutherans and Catholics. Calvinists continued to be persecuted by both groups.

The Treaty of Versailles was passed in 1919 and formally dissolved the formerly massive Empire of Austria-Hungary (one of the central powers, and losers, of World War One). The territory of Austria-Hungary was divided into smaller independent nations, including Austria, Hungary, Czechoslovakia, and Yugoslavia.

The Peace of Westphalia (1648) is one of the most important treaties in European history. It brought to an end the brutal fighting of the Thirty Years’ War that had devastated the population of German-speaking central Europe and pitted all the major continental powers of Europe against one another. It included formal religious tolerance for all three major branches of Protestantism, including Calvinism for the first time. It provided territorial gains for the Kingdoms of France and Sweden, who both emerged as dominant European powers during this time period. Finally, it provided de jure independence for the territory of Switzerland that had previously only enjoyed de facto independence.

The War of Austrian Succession and the Seven Years’ War both took place during the eighteenth century, whereas the Congress of Vienna took place in 1815, at the beginning of the nineteenth century; therefore, neither of these events contributed to the decline of the “Concert of Europe” in the time period described. The “Concert of Europe” refers to the balance of power implemented in Europe after the Napoleonic Wars designed to preserve peace and the status quo in Europe. It was negatively impacted by the Revolutions of 1848, which encouraged the rise of liberalism and democracy in Europe. It was also negatively impacted by the unifications of Germany and Italy, as two additional major powers emerged on the European scene concurrent with the decline of the Austro-Hungarian Empire.

After World War Two, the governments of France and West Germany wanted to integrate their economies so heavily that a future war would not only be impractical, but an economic impossibility. To this end, they integrated their coal and steel production communities under one umbrella organization. The original treaty was signed in 1951 by six countries: West Germany, France, Belgium, Italy, the Netherlands, and Luxembourg. It can be understood as the first step in the transnationalism that later led to the creation of the European Union.

The Congress of Vienna involved the shifting of Russian and Prussian borders, the confiscation of French territory gained after 1789, a guarantee of neutrality for Switzerland, and the general balance of power in Europe. King Charles X of France was not overthrown until the July Revolution of 1830.

The Treaty of Lausanne, signed in 1923 in Switzerland, ended the conflict between the Ottoman Empire and the World War I Allies. The Turks ceded much of the Ottoman Empire's territory in exchange for the Allies recognition of Turkey as a sovereign republic.

Germany lost Silesia, its colonies, its legal right to a substantial military, and was forced to sign the War Guilt clause of the Treaty of Versailles, which resulted in the discrediting of the German political left. While no Allied garrisons were established, France and Belgium would later occupy the Ruhr valley in 1923 to extract reparations.