The document provides background information on World War I (1914-1918), known as the Great War. It began in July 1914 after the assassination of Archduke Franz Ferdinand of Austria-Hungary and involved over 70 million military personnel across Europe and beyond. The war resulted from tensions between allies and an intricate system of alliances that turned a regional conflict over the assassination into a global war. It marked major technological advances and new, gruesome forms of industrialized warfare, as well as political changes across Europe in its aftermath.