While the rest of the world hated Europe's guts for being so rich, technologically and culturally advanced, and powerful, Europe committed that age-old human stupidity: instead of moving forward, squabble over what we have, because the weakest man in the group is nervous.
The result, World War I, was a disaster in that everyone who participated gained nothing and sacrificed themselves in a sociopathic display of mass suicide. "The War to End All Wars" may have been our first exposure to how in politics a pleasant lie is far more electable than a difficult truth. It's amazing democracy wasn't thrown out completely after that.
The number of World War I casualties, both military and civilian, was over 40 million — 20 million deaths and 21 million wounded. This includes 9.7 million military deaths and about 10 million civilian deaths. The Entente Powers (also known as the Allies) lost more than 5 million soldiers and the Central Powers about 4 million.
Even more is the damage to populations themselves. Austria-Hungary lost 1.1 million out of a population of 51.4 million; Germany lost 2 million out of 65 million. The French got really devastated: 1.4 million dead out of 40 million people. The Russians and the USA had negligible deaths in this regard, but the UK lost .9m from a population of 45m, so was somewhere in the middle.
This fratricidal war weakened Europe and created political conflicts that endure to this day, all in the name of some great liberal crusade to end nationalism -- one nation, one tribe -- and establish a Utopian order in which peace would prevail. What illusory empty goals, and yet the bigger the lie, the bigger the piles of bodies of otherwise good men.