- Manchukuo (1931) - Japan invaded Manchuria in 1931 and established the puppet state of Manchukuo.
- Ethiopia (1935) - Italy invaded Ethiopia in 1935, leading to the Second Italo-Ethiopian War.
- China (1937) - Japan launched a full-scale invasion of China in 1937, leading to the Second Sino-Japanese War.
- Austria (1938) - Nazi Germany annexed Austria in 1938, known as the Anschluss.
- Czechoslovakia (1938) - Germany invaded Czechoslovakia in 1938 and annexed the Sudetenland region, leading to the Munich Agreement.
- Albania (1939) - Italy invaded Albania in 1939, bringing the country under its control.
- Finland (1939) - The Soviet Union invaded Finland in 1939, leading to the Winter War.