Google "Cuban Missile War"
It's an insanely detailed "What if?" timeline of the nuclear war that could have resulted.
Its single point of departure from reality is a Russian sub commander, under extreme pressure, misinterpreting similar orders allowing nuclear-tipped torpedoes to be used, as commanding him to do so. The whole hellish scenario develops from there.

It's a chilling read if you have a couple of hours.
(North Utsira South Utsira, Thu 21 Jun 2012, 12:53, Reply)