World War 1 (1914-1919) By HelloZelda42 Period: Apr 21, 1913 to Apr 21, 1919 World War 1 Jun 26, 1913 Roger Fry established the Omega Workshops Jun 28, 1914 Assassination of Archduke Franz Ferdinand Aug 4, 1914 Great Britain declares war on Germany Aug 26, 1914 The battle of Tannenberg begins Oct 15, 1914 The battle of Ypres begins Dec 25, 1914 Christmas Truce on the Western Front Apr 22, 1915 German gas attack at Ypres May 7, 1915 Sinking of Lusitania Feb 21, 1916 Germans attack at Verdun Jul 1, 1916 Start of the Battle of the Somme Sep 15, 1916 First use of the tanks, in the Battle of the Somme Apr 6, 1917 United States declares war on Germany Jul 17, 1917 King George V changes his name to Windsor Oct 12, 1917 British attack at Passchendaele Nov 9, 1918 Kaiser Wilhelm II of Germany abdicates Nov 11, 1918 Armistice Jan 12, 1919 Paris Peace Conference Jun 28, 1919 Treaty of Versailles signed