| 1921 | 1935 |
| New Economic Policy in Soviet Union | Mussolini invades Ethiopia; creation of U.S. Works Progress Administration as part of New Deal |
| 1922 | 1936 |
| Mussolini seizes power in Italy | Start of great purges under Stalin; Spanish Civil War begins |
| 1924–1929 | 1936–1937 |
| Buildup of Nazi Party in Germany | Popular Front government in France |
| 1925 | 1939 |
| Hitler, Mein Kampf | Germany occupies Czech lands and invades Poland; Britain and France declare war on Germany, starting World War II |
| 1927 | 1940 |
| Stalin comes to power in Soviet Union | Japan signs formal alliance with Germany and Italy; Germany defeats France; Battle of Britain |
| 1928 | 1941 |
| Stalin’s first five-year plan | Germany invades Soviet Union; Japan attacks Pearl Harbor; United States enters war |
| 1929 | 1941–1945 |
| Start of collectivization in Soviet Union; Lateran Agreement | The Holocaust |
| 1929–1939 | 1944 |
| Great Depression | Allied invasion at Normandy |
| 1931 | 1945 |
| Japan invades Manchuria | Atomic bombs dropped on Japan; World War II ends |
| 1932–1933 | |
| Famine in Ukraine | |
| 1933 | |
| Hitler appointed chancellor in Germany; Nazis begin control of state and society | |