Dan's introduction from the beginning of the podcast is very reminiscent of the explanation offered by many historians for the importance of Gavrilo Princip. To quote a passage from Steven Pinker:
Writing in 1999, [historian Matthew] White repeated a Frequently Asked Question of that year: "Who's the most important person of the Twentieth Century?" His choice: Gavrilo Princip. Who the heck was Gavrilo Princip? He was the nineteen-year-old Serb nationalist who assassinated Archduke Franz Ferdinand of Austria-Hungary during a state visit to Bosnia, after a string of errors and accidents delivered the archduke to within shooting distance. White explains his choice:
Here's a man who single-handedly sets off a chain reaction which ultimately leads to the deaths of 80 million people.
Top that, Albert Einstein!
With just a couple of bullets, this terrorist starts the First World War, which destroys four monarchies, leading to a power vacuum filled by the Communists in Russia and the Nazis in Germany who then fight it out in a Second World War...
Some people would minimize Princip's importance by saying that a Great Power War was inevitable sooner or later given the tensions of the times, but I say that it was no more inevitable than, say, a war between NATO and the Warsaw Pact. Left unsparked, the Great War could have been avoided, and without it, there would have been no Lenin, no Hitler, no Eisenhower.