world war 1 By oliviastone Jun 26, 1914 Archduke Francis Ferdinand is assassinated. Jul 28, 1914 Austria-Hungary declares war on Serbia, beginning World War I. Aug 10, 1914 Austria-Hungary invades Russia. Sep 9, 1914 Allied forces halt German advance into France during First Battle of the Marne. Apr 25, 1915 Allied forces land on the Gallipoli Peninsula of the Ottoman Empire. May 7, 1915 German submarine sinks the passenger liner Lusitania during crossing from New York to Liverpool, England, killing 128 Americans. May 23, 1915 Italy declares war on Austria-Hungary. Feb 21, 1916 Germany begins the attack on Verdun. Aug 1, 1916 Allied offensive begins the Battle of the Somme. Dec 18, 1916 Battle of Verdun ends 550,000 French and 450,000 German casualties. Apr 9, 1917 The United States declares war on Germany. Dec 15, 1917 Russia signs armistice with Germany. Mar 3, 1918 Russia signs the Treaty of Brest-Litovsk with Germany. Mar 21, 1918 Germany begins its final offensive of the war. Sep 26, 1918 Allied forces begin the attack at Meusse-Argonne, the final offensive of the war. Nov 11, 1918 End of War Germany signs the Armistice at Compiègne, ending World War I.