I very much doubt anyone at the time thought the killing of a European royal would lead to the death of 17 million people.
History tells us what may happen next with Brexit & Trump
Tobias Stone

This event was the straw that broke the camel’s back. Europe had almost started WWI on multiple prior occasions, and always barely avoided it via diplomatic resolution. You’re a history professor and it surprises you that a war that had been building for almost a decade finally erupted…?