Answer:
The assassination of archduke Franz Ferdinand of Austria-Hungary
Explanation:
Archduke Franz Ferdinand of Austria-Hungary was in Bosnia when he was shot. A group of Serbs tried throwing bombs at his car, (which failed), and ended up hitting a police car. Later, Ferdinand was heading to the hospital the officers were at, and made a wrong turn. One of the assassins saw this and took the chance to shoot him. Austria gave Serbia a list of impossible demands and when denied, war was declared. Russia stepped in to help Serbia, and Prussia did the same for Austria. France, Belgium, Turkey, the UK, the USA, and several others got involved later.
