During the Renaissance, Italy consisted of five main city-states: Venice, Milan, Florence, the Papal States, and the Kingdom of Naples, each with its own system of government. There were struggles for power among these various political entities, and their internal and external struggles made Italy vulnerable to invasion. Continental powers (notably the French and Austrians under Charles V) fought for territorial control in Italy in the late fifteenth and sixteenth centuries.

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.

After the Napoleonic Wars were over an Austrian politician, Klemens Wenzel von Metternich, hosted a meeting of the major powers of Europe to decide how the redraw the map of Europe so as to avoid further wars like the Napoleonic Wars, which had brought Europe to the point of exhaustion.

The Holy Alliance was an alliance among the monarchs of Russia, Prussia and Austria. It was formed after the defeat of Napoleon in 1815 to combat democracy, secularism and revolution in Europe.

The North Atlantic Treaty Organization (NATO) was signed in 1949 following WWII in order to provide a safeguard against the Soviet Union and the spread of communist ideology. It was the first peacetime treaty the United States had ever signed.

The Treaty of Versailles (1919) officially ended the First World War, then known simply as "The Great War." Its harsh treatment of the Central Powers, including forcing Germany to pay steep reparations and accept full responsibility for the war, contributed to the rise of radical factions (including the Nazis) in Germany in the 1920's and '30's.

The term “Asiento” is a Spanish term that in British history is used to refer to an arrangement made in the 1713 Peace of Utrecht that Britain was to be given a forty-year contract to provide slaves to the Spanish colonies of the New World. The “Asiento” was an extremely lucrative contract because it gave the British a near monopoly on the valuable sale of goods and slaves to Spanish colonists.

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 union of Lublin unified the two nations of Poland and Lithuania into one nation under the Jageillonian Dynasty

The Union of Kreva saw the marriage of the Grand Duke of Lithuania to the daughter of the recently passed Polish king. Jadwiga had no brothers so she was crowned King of Poland, set to rule until she married. Her mother then arranged a marriage with the leader of Lithuania, the Grand Duke Jogalia, thus joining the royal lines of Poland and Lithuania.