World War I
World War I, called the Great War until the occurrence of World War II, lasted from July 28, 1914 until November 11, 1918.
It involved all the major and economically developed countries, centering in Europe and spanning the globe from Africa to the Middle East as well as North and South America.
It started when the Austrian Archduke Franz Ferdinand was assassinated by Gavrilo Princip of Yugoslavia. Within weeks, the Allies and the Central Powers (namely Germany, Austria-Hungary, and the Ottoman Empire) had been roped into international war that eventually involved 70 million military personnel and killed over 9 million people.