World War 1 began in 1914 and lasted until 1918. It started in the Balkans due to the assassination of Archduke Franz Ferdinand of Austria-Hungary by Serbian nationalists. The two initial countries involved were Serbia and Austria-Hungary. Major powers aligned into two coalitions, the Allied powers including France, Russia, Italy, and Britain, and the Central Powers including Germany, Austria-Hungary, the Ottoman Empire, and Bulgaria. Germany launched the Schlieffen Plan at the beginning of the war but it failed to quickly capture Paris. The war became a stalemate characterized by trench warfare and total mobilization of resources. Key battles included Gallipoli and Verdun. The United States entered