What event had led to the expansion of participatory democracy in the first half of the nineteenth century?

Social and economic changes of the nineteenth century

Explanation:

Given the victory of the allies in the world war 1, the ancient systems of aristocratic leadership, oligarchy and monarchy ceased to be legitimate following the defeat of Italy and Germany in world war 2, the newer alternatives of fascism was annulled with the Soviet style communism after the fall of the political and economy of USSR which contributed to the disappearance of dictatorship and military rule.