A 19-year-old Serbian student, Gavrilo Princip, assassinated Archduke Franz Ferdinand of Austria in Sarajevo in June 1914. This sparked World War I as Serbia was allied with Russia against Austria-Hungary who was allied with Germany. The war was fought across Europe along borders between France-Germany, Germany-Russia, and Austria-Italy. It also spread to colonies in Africa and the Pacific. Germany lost naval battles in the North Sea and its submarine attacks on civilian ships like the Lusitania led the US to join the Allies against Germany in 1917.