| 1914 | Assassination of Archduke Franz Ferdinand; Ottoman Empire joins Central Powers; German victories on the eastern front |
| 1914–1918 | World War I |
| 1914 | Japan joins the Triple Entente and seizes German holdings in China |
| 1915 | Italy joins the Triple Entente; German submarine sinks the Lusitania; Japan expands into southern Manchuria |
| 1916 | Battles of Verdun and the Somme; Irish Easter Rebellion; German Auxiliary Service Law requires seventeen- to sixty-year-old males to work for war effort; Rasputin murdered |
| 1916–1918 | Growth of antiwar sentiment throughout Europe |
| 1917 | United States declares war on Germany; Bolshevik Revolution in Russia |
| 1917–1922 | Civil war in Russia |
| 1918 | Treaty of Brest-Litovsk; revolution in Germany |
| 1919 | Treaty of Versailles; Freudian psychology gains popularity; Rutherford splits the atom; Bauhaus school founded |
| 1920s | Existentialism, Dadaism, and surrealism gain prominence |
| 1923 | French and Belgian armies occupy the Ruhr |
| 1924 | Dawes Plan |
| 1926 | Germany joins League of Nations |
| 1928 | Kellogg-Briand Pact |