The Middle East played a large role in World War 1. Their sultan declared a military jihad (holy war) against France, Russia and Great Britain during World War 1.
Austria-hungary attacked Serbia
The assassination of Archduke Franz Ferdinand of Austria-Hungary by Serbian nationalists.
The Treaty of Versailles.
The sinking of the Lusitania pushed the United States into the war.
European countries entered into military alliances that required them to protect one another from attacks