1. A new Great power
US became a new military power apart from being an economic power.
2. Socialism rise to the world stage
Collapse of Russia brought the socialism to the world stage. Soon powerful communist nation in Europe and Asia changed the balance of world politics.
3. The Collapse of Central and Eastern European Empires
The German, Russian, Turkish and Austro-Hungarian Empires all fought in World War One, and all were swept away by defeat and revolution (although not necessarily in that order). The fall of Turkey (in 1922, from a revolution stemming directly from the war) and Austria-Hungary were probably not that much of a surprise:
4. Nationalism Transforms and Complicates Europe
The key region for European nationalism was Eastern Europe and the Balkans. Nationalism conflicted hugely with the ethnic make-up of this region of Europe, where many different nationalities and ethnicities all lived merged with one another, and where self-determination and national majorities created disaffected minorities who preferred the rule of a neighbour.
5. The Myths of Victory and Failure
The myth of the undefeated German army being ‘stabbed in the back’ by liberals, socialists and Jews which damaged Weimar and fuelled the rise of Hitler .
Italy didn’t receive as much land as it had been promised in secret agreements, and right wingers exploited this to complain of a ‘mutilated peace’.
In contrast, in Britain the successes of 1918 which had been won partly by their soldiers were increasingly ignored, in favour of viewing the war, and all war, as a bloody catastrophe. This affected their response to international events in the 1920s and 30s; arguably, the policy of appeasement from born from World War One.