According to Robert Krulwich in “You (and Almost Everyone You Know) Owe Your Life to This Man” about Vasili Alexandrovich Arkhipov
The debate between the captain and Arkhipov took place in an old, diesel-powered submarine designed for Arctic travel but stuck in a climate that was close to unendurable. And yet, Arkhipov kept his cool. After their confrontation, the missile was not readied for firing.
Looking back, it all came down to Arkhipov. Everyone agrees that he’s the guy who stopped the captain. He’s the one who stood in the way.
Nuclear weapons are inherently dangerous. […] the world is very, very lucky that at one critical moment, someone calm enough, careful enough, and cool enough was there to say no.