When the countries elected new leaders for their countries, the new leaders didn't necessarily follow the rules and other things that the previous leader believed and followed. So when new leaders came into office, they had their own thoughts and ideas about how the country should be run.
Europe
I am afraid not to understand the question. Do you mean Europe as a political entity (European Union) or Europe as a continent ?
Europe declined in political power as empires crumbled and monarchies were replaced by democracies. There was an economic deterioration of Europe and radical revolutionary groups and movements emerged that would greatly change the political landscape of Europe. Excessive, punitive economic actions against Germany led to a wrecked economy and resentments that would eventually give rise to World War II.
Because Hitler claimed that the Sudetenland was the last territorial claim that he have to make in Europe. They believed Hitler & they were hoping to avoid the war.
Europe
New political leaders were elected, and they helped to turn their respective countries around and build them up to where they were before the war.
The political leaders of the Big 3 and other allied force leaders decided how the borders would be drawn in Europe and Korea.
Antony Black has written: 'Political thought in Europe, 1250-1450'
to decide the terms boundaries of post war europe
They both thought they could take Russia in the middle of Winter and wanted an Empire that spanned most of Europe.
Political changes in eurpe after world war 1
Europe is a continent with over 50 countries. Each of those countries have their own leaders. So there are a lot more than three leaders in Europe.
The political structure of medieval Europe is Feudalism.
Machiavelli's work, such as "The Prince," challenged traditional ideas of politics and morality. These ideas influenced political thought during the Renaissance and continue to shape discussions on power and governance today. His emphasis on realism and practicality have had a lasting impact on how leaders approach decision-making and governance.
Peasants provided European leaders with enough labor.
The first settlers of Europe are thought to be Neanderthals, before the last Ice Age 10,000 years ago.