Which events of the second half of the XX century were most likely to diverge. The simpler the change and the larger the long term change, the better. The first one that comest to mind is Stanislav Petrov and the faulty Soviet nuclear early-warning systems. Although I doubt that is as easy as people suspect beacause:
"Petrov later indicated that the influences on his decision included: that he was informed a U.S. strike would be all-out, so five missiles seemed an illogical start that the launch detection system was new and, in his view, not yet wholly trustworthy; and that ground radar failed to pick up corroborative evidence, even after minutes of delay."\
Anyways, any other suggestions?
"Petrov later indicated that the influences on his decision included: that he was informed a U.S. strike would be all-out, so five missiles seemed an illogical start that the launch detection system was new and, in his view, not yet wholly trustworthy; and that ground radar failed to pick up corroborative evidence, even after minutes of delay."\
Anyways, any other suggestions?