On June 28, 1914, Archduke Franz Ferdinand and his wife Sophie were assassinated in Sarajevo by 19‑year‑old Serbian nationalist Gavrilo Princip, triggering a diplomatic crisis that escalated into war.
Within a month Austria‑Hungary declared war on Serbia, and the system of alliances pulled almost every great power of Europe into conflict. The war, which lasted until 1918, claimed more than 16 million lives and led to the collapse of the Austro‑Hungarian, Ottoman, German, and Russian empires.
The reshaping of Europe after the war set the stage for the Second World War, making the Sarajevo assassination one of the most pivotal events in modern history.