WWI was caused by the French Revolution
Bill White writes:
The Austro-Hungarian Empire [1867-1918] was the first unwanted experiment of a unified Middle Europe. It consisted of such diverse national groups with different languages and backgrounds as Italian, Romanian, Slovakian, Serbian, Croatian, German, and Hungarian. As long as these groups were antagonizing each other, the Hapsburgs of Austria could impose their authority. But as soon as efforts of agreement and union were successful, the Hapsburgs lost control. [The liberal Lajos] Kossuth was wise enough not to see enemies in the surrounding nationalists who spoke another language Kossuth cherished a dream of a a Danube Basin Confederation to connect all states situated on the Danube into a political-cultural-commercial unity of friendship and common interest. What he dreamed was a seed for a future United States of Europe. Joseph Domjan, Hungarian Heroes and Legends, 1963. (Example of liberal propaganda in a children's book.)There's more truth to this than people think. The attempt to unify different nations based on ideology was fundamentally a liberal trope, because once you deposed natural aristocracy and replaced culture with ideological concerns, the only ability to unite people was politics. This is how WWI was a direct result of the French Revolution.