1914-1918 By WilleNater45 Feb 4, 1914 Germany declares a "war zone" around Great Britain, Aug 3, 1914 Germany declares war on France. Aug 19, 1914 President Woodrow Wilson says the U.S will not fight yet Aug 26, 1914 The Battle of Tannenberg is started Dec 24, 1914 The unofficial Christmas truce is declared. Apr 22, 1915 The Second Battle of Ypres the battle that the Germans first use poison gas. May 31, 1916 The Battle of Jutland, the major naval battle of the war, Jul 1, 1916 Battle of the Somme, tanks are first introduced Apr 6, 1917 The United States declares war on Germany. Apr 21, 1918 German pilot Baron Manfred von Richthofen (Red Baron), is shot down.