You could say a duke died and it would still work for the first one. Like, the second one had a much more streamlined cause, but the first one wasn't some complex problem either.
I mean sure, a duke died, but it was the last straw in an era of extreme political tension. In short, everyone had beef with everyone, and many countries had to deal with internal beef on top of that, like uprisings and stuff.
That said the causes of WWII are similarly complex. Germany was hit hard by the Versailles treaty, its economy and people's spirit crippled, and France just couldn't fucking be done bullying it (sounds like the plot leading up to a school shooting, doesn't it). A conspiracy theory called the Dolchstosslegende developed among the Germans, blaming their WWI loss not on external factors, but on traitors on the inside - Jews, communists etc. (during the war the German press kept printing that Germany was winning, so the people were shocked when it lost the war) This played right into the Nazis' hand, with their mysticism and shit. It's too complex for one comment but TL;DR the narrative that WWII can be blamed on one country or even one person is BS.
That said the causes of WWII are similarly complex. Germany was hit hard by the Versailles treaty, its economy and people's spirit crippled, and France just couldn't fucking be done bullying it (sounds like the plot leading up to a school shooting, doesn't it). A conspiracy theory called the Dolchstosslegende developed among the Germans, blaming their WWI loss not on external factors, but on traitors on the inside - Jews, communists etc. (during the war the German press kept printing that Germany was winning, so the people were shocked when it lost the war) This played right into the Nazis' hand, with their mysticism and shit. It's too complex for one comment but TL;DR the narrative that WWII can be blamed on one country or even one person is BS.