What year did World War I begin?

World War I began in 1914, conventionally dated from Austria-Hungary’s declaration of war on Serbia on 28 July.

The conflict followed the assassination of Archduke Franz Ferdinand in Sarajevo on 28 June 1914. Austria-Hungary blamed Serbia and sent an ultimatum. When the crisis escalated, Austria-Hungary declared war, activating a wider confrontation among Europe’s rival powers.

Russia mobilized to support Serbia. Germany then declared war on Russia and France, while Britain entered after Germany invaded Belgium in early August. The war expanded from Europe into the Middle East, Africa, and the Asia-Pacific, becoming a genuinely global conflict.

The war lasted until 11 November 1918, when the armistice with Germany took effect. It is also called the Great War or the First World War. A frequent mistake is to date its beginning to 1913, when the Balkan Wars were still reshaping southeastern Europe, or to 1916, by which time major battles such as Verdun and the Somme were already underway.