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.
The war changed the economical balance of the world, leaving European countries deep in debt and making the U.S. the leading industrial power and creditor in the world. ... WW1 boosted research in technology because better transport and means of communication gave countries an advantage over their enemies.
