What was the most significant impact of World War 1?

WW1 created every consequences that led to WW2. The war left European countries in debt and made the U. S the leading industrial creator in the world, Inflation also shot hp in most countries and the German economy was highly affected since they had to pay for reparations.

WW1 caused the downfall of four monarchies: Germany, Turkey, Austria-Hungary and Russia. The war made people more open to other ideologies, such as the Bolsheviks that came to power in Russia and fascism that triumphed in Italy and even later in Germany.