World War I began on 28 July 1914 and ended on 11 November 1918. This war is also called as the Great War, and it happened in Europe. Many of the countries, which had the world's great powers, has participated in this war separated into two opposing alliances, the Allies and the Central Powers. In the Allies, there were United Kingdom, France, Russia and in the Central Powers, there were Germany, Austria-Hungary, Italy. Many people had suffered from this life, since it killed about 9 million people. Many people believe that the World War I started because of these four reasons, Militarism, Alliances, Imperialism, and Nationalism. Different countries wanted to show that they are the strongest country, so they wanted to fight others to prove that they are the strongest. Countries started to build up strong armies, which is nationalism and militarism. Also, since countries were alliances to different countries, when one country participated in the war, others had to support them. Not only this but World War I also happened because of the assassination of Archduke Franz Ferdinand.