Normally, on Soviet subs the order to launch nuclear weapons needed two approvals: That of the Captain and the Political Officer. IIRC Arkhipov was fleet Commander though and used the "attacked" submarine (when they tried running the blockade of Cuba the US Navy started pestering them with training depth charged to make them surface - which underwater felt like real ones) as his flagship. So launching a nuclear Torpedo on that particular ship required three approvals as to not override the most senior officer on board.

Chilling. Absolutely chilling to think about it.