World War One began after the assassination of Archduke Ferdinand of Austria-Hungary by a Serbian nationalist. This caused alliances to form between countries in Europe. The Central Powers of Germany, Austria-Hungary and the Ottoman Empire fought against the Allied Powers of Britain, France, Russia and later the United States. Over 15 million soldiers and civilians lost their lives in the war. The war also coincided with the 1918 influenza pandemic which killed approximately 50 million people worldwide.