Who Started World War I - S2.E10

In which John Green teaches you WHY World War I started. Or tries to anyway. With this kind of thing, it's kind of hard to assign blame to any one of the nations involved. Did the fault lie with Austria-Hungary? Germany? Russia? Julius Caesar? One thing we can say for sure is that you can't blame the United States of America for this one. Woohoo! Well, you can hardly blame the US.