Several times during the Cold War, the World came dangerously close to a nuclear disaster.
In 1961 and 1968, B52 Bombers carrying nuclear bombs met with accidents nearly leading to a nuclear catastrophe. In 1983, one Soviet Lt. Col. single handedly saved the world from WWIII when he categorized an alarm about 5 missiles being launched at the Soviet Union, a false alarm.
NATO conducted a WWIII simulation in 1983, which the Soviets assumed, was cover for an actual nuclear strike from the West.