The First World War took place between 1914 and 1917 and was fought between the Allies and the Central Powers.
In June 28, 1914, Archduke Franz Ferdinand, heir to the Austria-Hungary throne, and his wife Sophie were shot dead by assassin Gavrilo Princip, a Serb nationalist.
Tensions quickly rose among the European powers when monarchs and governments began taking sides, mainly because they were involved in treaties which obligated them to defend their allies and ententes during international conflicts. During the days following the assassination, Austria-Hungary openly promoted Serb discrimination, causing the Russian Empire to condemn such racism as the Serbs were of Slavic ethnicity. In turn, the German Empire backed Austria-Hungary by condemning the Serb movement as terrorism. Great Britain and France soon back Russia, forming the "Triple Alliance" to fight the "Central Powers" Germany and Austria-Hungary.
The war officially began at Archduke Ferdinand's one-month anniversary at July 28, 1914. Although Austria-Hungary only declared war on Serbia, Germany, Britain, Russia, France, and the Ottoman Empire (now Turkey) would eventually join the fray.
The Central Powers - Germany, Ottoman Empire, and Austria-Hungary, eventually surrendered after continued United States involvement.
Many historians agreed that the Allies were too excessive in punishing the Central Powers. The Treaty of Versailles burdened them, especially Germany, with unrealistic requirements to pay post-war reparation costs and military restrictions which sparked more aggression rather than humble the defeated nations.
Dictators such as Adolf Hitler and Benito Mussolini would later use the Treaty to rally major support in a second great conflict.
However, the war, aside from dissolving the German and Austria-Hungary Empires, also weakened the Allied Powers' dominion over their colonies and protectorates. In the midst of the British Empire's weakened state, the United States of America rose as a second superpower. President Woodrow Wilson used this momentum to found and foster the growth of the world's premier peacekeeping organization - the League of Nations. Although the League's fate was little better than the German Empire, other world leaders would become weary of war and adopt Wilson's ideals.