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