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 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 Battle of Waterloo, one of the most famous battles in history, was the final defeat of Napoleon Bonaparte by a joint force under the command of Generals Arthur Wellesley and Gebhard von Blucher (who were British and Prussian, respectively). The campaign began when Napoleon returned from his initial exile on the Island of Elba in 1815. After Waterloo, Napoleon would again be exiled, but this time to the much more distant island of St. Helena and under much tighter security. After his second exile Napoleon Bonaparte never regained his power or status.

The Seven Years’ War took place from 1756 until 1763 between the French and British Empires. It was fought all over the world, as at this time the colonial possessions of Britain and France were nearly everywhere. The war ended with British victory and in America resulted in the complete loss of French possessions in Canada and the North. This would have significant consequences, providing the motivation and circumstance for revolution. It also gave the British control of French holdings on the Indian subcontinent. The Seven Years War thus, while being a European War, had truly global consequences.

The Fourth Crusade lasted from 1202 to 1204. The crusaders entered into an agreement with Byzantine prince Alexios Angelos. The crusaders made a deal to help reinstate his father as emperor of Constantinope, and the Byzantines would offer them payment and military support.

The crusaders were successful in holding up their side of the bargain, but in 1204 the emperor was deposed and the crusaders did not receive their end of the bargain. Following this, the crusaders decided to conquer the city outright.

The Treaty of Versailles (1919) officially marked the end of WWI between Germany and the Allied Powers.

As part of the treaty, Germany (and her allies to a lesser extent) was to take sole responsibility for causing all of the damage and destruction of the Great War. Germany was required to give up extensive land rights, disarm their military, and pay reparations totaling what would amount to US $442 billion in today's terms.

The Nuremberg trials were a famous set of 13 trials held between 1945 and 1949 with the purpose of prosecuting Nazi war criminals. They were held in the German city of Nuremberg.

Some well-known Nazi figures that were tried in Nuremberg were Hermann Goering, Rudolf Hess, Wilhelm Keitel, Albert Speer, and Joachim von Ribbentrop.

The Triple Entente was the alliance originally formed between France, Russia, and Great Britain to stand against the Triple Alliance of Germany, Austria-Hungary, and Italy. This complex alliance system became the political powder-keg that would explode into World War I after the assassination of the Archduke of Austria, Franz Ferdinand. The other answers are incorrect combinations of allied and enemy nations.