The book "One Minute to Midnight" about the Cuban Missile Crisis has a rather long list of places during that confrontation that almost led to nuclear war.
http://www.amazon.com/One-Minute-Midnight-Kennedy-Khrushchev...
One fascinating one was a U2 getting lost on the way to the North Pole due to the Northern Lights and flying back into the Soviet Union just at the wrong time - alarming the Soviets and resulting in fighters being sent up by the US to protect the ailing U2. Unfortunately, due to the US being at Defcon 2 the fighters were only armed with nuclear air-to-air missiles.... The relief (for a number of reasons) the U2 pilot felt when he eventually landed was, understandably, rather intense!
Amazing book about a ghastly time.
My favourite anecdote is the code on all warheads on the US' Minuteman fleet being set to 00000000 as an exercise in simultaneously conforming to and circumventing requirements for PALs (locks to forbid misuse).
[1] : http://www.motherjones.com/politics/2013/08/eric-schlosser-c...