WWI By skyrim3197 Jun 28, 1914 Assassination of Archduke Franz Ferdinand Jul 5, 1914 Austria-Hungary seeks German support for war Approved Jul 23, 1914 Austria-HUngary sends an ultimatum to Serbia Response seen as unsatisfactory Jul 28, 1914 Austria-Hungary declares war on Serbia Aug 1, 1914 Germany declares war on Russia Aug 3, 1914 Germany declares war on France Aug 4, 1914 Germany invades Belgium Aug 4, 1914 The United Kingdom declares war on Germany Aug 5, 1914 Montenegro declares war on Austria-Hungary Aug 6, 1914 Austria-Hungary declares war on Russia Aug 6, 1914 Serbia declares war on Germany Aug 9, 1914 Montenegro declares war on Germany Aug 11, 1914 France declares war on Austria-Hungary Aug 12, 1914 The United Kingdom declares war on Austria-Hungary Aug 22, 1914 Austria-Hungary declares war on Belgium Aug 24, 1914 Japan declares war on Germany Aug 25, 1914 Japan declares war on Austria-Hungary Nov 1, 1914 Russia declares war on Ottoman Empire Nov 3, 1914 Montenegro declares war on Ottoman Empire Nov 5, 1914 France and the United Kingdom declare war on Ottoman Empire Period: Apr 22, 1915 to Apr 25, 1915 First use of poison gas German use May 23, 1915 Italy declares war on Austria-HUngary Oct 14, 1915 Bulgaria declares war on Serbia Oct 15, 1915 The United Kingdom declares war on Bulgaria Oct 16, 1915 France declares war on Bulgaria Oct 19, 1915 Italy and Russia declare war on Bulgaria Mar 9, 1916 Germany declares war on Portugal Aug 27, 1916 Romania enters war on Entente side Aug 27, 1916 Italy declares war on Germany Period: Sep 15, 1916 to Sep 22, 1916 British use armored tanks for first time in history Apr 6, 1917 USA declares war on Germany Jun 30, 1917 Greece declares war on Central Powers Dec 7, 1917 USA declares war on Austria-Hungary Dec 23, 1917 Germany and Russia sign an armistice Jan 8, 1918 Woodrow Wilson outlines his 14 points May 21, 1918 Ottomans invade Armenia Sep 30, 1918 Bulgaria signs an armistice with the Allies Oct 30, 1918 Ottoman Empire sign the armistice of Mudros Nov 3, 1918 Austria-Hungary signs the armistice with Italy Nov 11, 1918 Germany signs armistice of Compiegne Nov 25, 1918 Germany officially surrenders Period: Jan 18, 1919 to Jul 21, 1919 Treaty of Versialles Jan 10, 1920 Official end of WWI