June 28, 1914: a Serbian nationalist shot and killed Austrian Archduke Franz Ferdinand and his wife. Though many long range causes existed, this event would launch WWI.
The assassination of the Archduke and his wife took place in Sarajevo, the capital of Bosnia, a part of the Austro-Hungarian Empire. The assassin, Gavrilo Princip, was a member of the Serbian secret organization, the Black Hand. The Black Hand sought to throw off Austrian rule and unite Bosnia with Serbia.
Upon learning of the Archduke's planned visit, the Black Hand began to plot the assassination as a way of demonstrating their hatred of Austrian control of Serbs. A bombing was planned and carried out early in the day of the royal visit, but failed. Though many spectators were killed as the bomb missed the royal automobile, Ferdinand decided to continue his visit.
After giving a speech in the Sarajevo town hall, Ferdinand insisted on visiting a hospital where those injured in the earlier incident were being treated. Upon leaving, the Archduke's driver made a wrong turn and headed down a narrow side street. Here, Princip, fired two shots and killed Ferdinand and his wife. Four weeks later, Austria declared war on Serbia.
Within weeks, six nations would be at war. By the end of the conflict, dozens of nations would be at war with some 10 million soldiers dead and 21 million more wounded.