World War I officially began in 1914. The assassination of Archduke Franz Ferdinand of Austria on June 28 sparked a series of events that led to the war. Following Austria-Hungary’s declaration of war on Serbia on July 28, alliances formed between major powers drew numerous countries into conflict. By August 4, Germany invaded Belgium, prompting Britain to declare war on Germany. The war involved many of the world’s great powers as they took sides, and it lasted until November 11, 1918, leading to significant loss of life and widespread destruction, reshaping political boundaries and international relations in the process.