28 July 1914 – 11 November 1918

Albania, Arabia, Austria, Hungary, Brazil, Bulgaria, China, Cuba, Czechoslovakia, Estonia, Finland, France and, Great Britain, Germany, Greece, Guatemala, Haiti, Honduras, Italy, Japan, Latvia, Liberia, Lithuania, Luxembourg, Montenegro, Nicaragua, Panama, Persia, Philippines, Poland, Portugal, Russia, Serbia, Siam, Turkey and the United States of America.

the assassination of Austria's Archduke Franz Ferdinand and his wife Sophie. The assassination occurred on June 28, 1914 while Ferdinand was visiting the city of Sarajevo in the Austro-Hungarian province of Bosnia-Herzegovina.