| 1914–1918 | World War I |
| June 28, 1914 | Serbian nationalist assassinates Archduke Franz Ferdinand |
| August 1914 | War begins |
| September 1914 | Battle of the Marne; German victories on the eastern front |
| October 1914 | Ottoman Empire joins the Central Powers |
| 1915 | Italy joins the Triple Entente; German submarine sinks the Lusitania; Germany halts unrestricted submarine warfare; Battle of Gallipoli |
| 1915–1918 | Armenian genocide; German armies occupy large parts of east-central Europe |
| 1916 | Battles of Verdun and the Somme |
| 1916–1918 | Antiwar movement spreads throughout Europe; Arab rebellion against Ottoman Empire |
| 1917 | Germany resumes unrestricted submarine warfare |
| March 1917 | February Revolution in Russia |
| April 1917 | United States enters the war |
| October–November 1917 | Battle of Caporetto |
| November 1917 | Bolshevik Revolution in Russia; Balfour Declaration on Jewish homeland in Palestine |
| 1918 | Treaty of Brest-Litovsk; revolution in Germany |
| 1918–1920 | Civil war in Russia |
| 1919 | Treaty of Versailles; Allies invade Turkey |
| 1923 | Treaty of Lausanne recognizes Turkish independence |