 On 28 June 1914 , the heir to the throne of Austria @-@ Hungary , Archduke Franz Ferdinand , was assassinated by the Bosnian @-@ Serb Gavrilo Princip in the name of Serbian nationalism . This caused a diplomatic crisis resulting in Austria @-@ Hungary declaring war on Serbia and sparking the First World War . Due to a variety of reasons , within weeks the major powers of Europe — divided into two alliances known as the Central Powers and the Triple Entente — were at war . As the conflict progressed , additional countries from around the globe were drawn into the conflict on both sides . 
