It wasn’t just what happened in 1914. That was simply the dénouement. Decades of passivity, ambiguity, and pusillanimity in the face of German aggrandizement and daring predated that fateful year.
Aggrandizement? Not so in the first world war. Yes there was a buildup, but the man who put it all together saw the cornerstone of Germany freedom was his alliance with Austria and Russia. The League of 3 Emperors.
The Kaiser screwed that all up by pushing the Russians to ally with France. Prior to that Germany and Britian had been allies against France.