World War One, also known as the First World War or the Great War, began on July 28, 1914, and ended on November 11, 1918. It started after the assassination of Archduke Franz Ferdinand of Austria-Hungary on June 28, 1914, which led Austria-Hungary to declare war on Serbia. This triggered a chain of alliances activating many countries into the conflict, including Germany, Russia, France, the United Kingdom, and later the United States among others. The war was fought primarily in Europe but also affected other regions globally.