History By deop 1882 Triple Alliance Formed 1907 Triple Entente Formed Jun 28, 1914 Murder of the Archduke Frank Ferdinand Jul 28, 1914 Austrohungary declares war on Serbia Aug 1, 1914 Chain of war declarations Aug 2, 1914 Germany Invades Belgium Sep 6, 1914 First Battle of Marne Oct 19, 1914 Battle of Ypres Feb 21, 1916 Battle of Verdun Jul 1, 1916 Battle of Somme Apr 6, 1917 The US joins the war Jun 28, 1919 Treaty Of Versailles Jan 10, 1920 League Of Nations