Answer:
(a) The Treaty of Versailles: After the First World War the victorious Allies imposed the Treaty of Versailles (1919) on Germany. Germany was held guilty of the war, lost territory and all its colonies, had to pay huge reparations, its army was limited and the Rhineland was demilitarised. Germans felt humiliated and wanted revenge, which Hitler used to gain power.
(b) Fascism and Nazism: Mussolini established Fascist rule in Italy (1922) and Hitler’s Nazi Party came to power in Germany (1933). Both believed in extreme nationalism, dictatorship, militarism and expansion by force. Hitler broke the Treaty of Versailles, rearmed Germany, occupied the Rhineland, annexed Austria and Czechoslovakia, and invaded Poland on 1 September 1939, starting the war. Italy invaded Ethiopia; Germany, Italy and Japan formed the Axis.
(c) Failure of the League of Nations: The League was set up to keep peace but was weak. The USA never joined, and it had no army of its own. It could not stop Japan’s invasion of Manchuria (1931), Italy’s attack on Ethiopia (1935) or Hitler’s aggression; aggressor nations simply left the League. Britain and France followed a policy of appeasement (Munich Pact, 1938). The League’s failure encouraged the dictators and the Second World War broke out.