Inflection point
A lot was happening in those days, the Cold War, Apollo, Viet Nam, civil rights, the Beatles were right around the corner, but if you had to pick a moment, a single precise instant, when everything changed, that was it. Oswald did change the world, I wonder if he changed it in the way he expected.
There's a lesson there, one we've obviously never learned. If you are ever given the opportunity to change the world with one single irretrievable act, be very very careful...