when did ww1 happen

World War I happened from July 28, 1914, to November 11, 1918. It began after the assassination of Archduke Franz Ferdinand of Austria-Hungary and involved major powers grouped into the Allies and Central Powers. The war ended with the armistice on November 11, 1918, which marked the ceasefire, and was followed by the Treaty of Versailles in 1919 that officially ended the conflict.