When was start world war I first ?

World War I started on July 28, 1914. The conflict began with the Austro-Hungarian Empire’s declaration of war against Serbia, following the assassination of Archduke Franz Ferdinand, the heir to the Austro-Hungarian throne, on June 28, 1914. The war quickly escalated as various alliances and treaties were invoked, leading to a widespread conflict that involved many nations. The war lasted until November 11, 1918, when an armistice was signed, ending the fighting.