Notably, all of the closest calls to a World War 3 regard the stand-off between the two nuclear superpowers, the Soviet Union and the United States.
Here are some of the dates when a nuclear war almost happened, and some of the names that helped prevent it.
A lonely sub
In October 1962, at the peak of the Cuban Missile Crisis, four diesel-powered Soviet subs deployed to the Caribbean to escort warships that carried nuclear weapons to Cuba.
Unbeknownst to the US, each submarine was armed with 22 torpedoes, including a nuclear-tipped one with an explosive force nearly equal to that of the Hiroshima bomb. The sailors were told they could use it if an enemy damaged the vessel or if Moscow gave a special order.
On Saturday, 27 October, one of the subs, the B-59, was detected and encircled by a fleet of American aircraft carriers. The US forces began dropping practice depth charges to try and force it to float up so it could be identified.
The sailors, who had had no contact with Moscow for days, were in extremely stressful conditions, with low batteries causing extreme heat and increased levels of carbon dioxide on board.
It appears that the captain, Valentin Savitsky, lost his temper and was about to launch a nuclear torpedo believing that a war had started between the Soviet Union and the US. However, such a move required approval from two other senior officers on board: the political officer Ivan Maslennikov, and the flotilla commodore Vasily Arkhipov.
Maslennikov did not object, but Arkhipov convinced fellow officers to surface and wait for a signal from Moscow. The following day, the Soviet Union and the US reached an agreement to withdraw their missiles from Cuba and Turkey, respectively, and the crisis ended.
The story hadn’t been made public for 40 years; the sailors didn’t like to remember it because the Soviet leadership apparently was angry that the sub revealed itself in the first place.
Vadim Orlov, who was in charge of radio communications on the B-59, told the story of Arkhipov’s action in 2002, four years after the decorated commodore passed away.
If he had authorised the launch, it would like have triggered reciprocal action from the United States and a Third World War. 27 October 1962 went down in history as Black Saturday, the day that mankind came the closest to a nuclear war.
A stray bear
Just days earlier another event with potentially apocalyptic repercussions happened hundreds of miles away from Cuba, at a direction centre in Duluth, Minnesota.
At around midnight on 25 October, a guard saw a shadowy figure climbing the security fence. He shot at the intruder, who he thought could be a Soviet agent, and pulled the sabotage alarm, which was also automatically triggered at nearby bases.
But the sabotage alarm was miswired at the Volk Field air base, and the Klaxon went off instead, ordering two squadrons of nuclear-armed F-106A interceptors to take off and look out for Soviet bombers.
The mishap took place while the army was on high alert at DEFCON 3, and pilots believed it wasn’t a drill but the start of a war. There was a chance that they could’ve mistaken friendly bombers for enemy ones as well.
While the fighter jets were starting down the runway, Volk Field contacted Duluth and discovered the error.
A solar storm
On 23 May 1967, an intense solar storm – one of the largest blasts of radiation from the Sun’s surface on record – tampered with a set of American surveillance radars in the far Northern Hemisphere, used by the military to detect incoming Soviet missiles.
Assuming they had been jammed by the USSR (something tantamount to an act of war), the Air Force authorised the mobilisation of aircraft and nuclear-equipped troops to retaliate against the Soviet Union.
At the last minute, a group of scientists stepped in and showed that the radars were actually disrupted by the Sun, not the Soviets.
“Had it not been for the fact that we had invested very early on in solar and geomagnetic storm observations and forecasting, the impact [of the storm] likely would have been much greater,” said space scientist Delores Knipp, who broke the story in 2016. “This was a lesson learned in how important it is to be prepared.”
A big gamble
The Cold War ushered in a period of détente in the 1970s, but reignited again with the beginning of the Soviet-Afghan War.
A faulty missile launch warning system nearly led to a global conflict again in September 1983, when tensions between the USSR and the United States spiked following the downing of a South Korean passenger jet that had strayed into Soviet airspace.
Overnight from 25 to 26 September, Stanislav Petrov, a 44-year-old lieutenant colonel, was on duty at a secret command centre outside Moscow monitoring Soviet early-warning satellites over the US.
He saw that Soviet computers warned about the launch of five intercontinental ballistic missiles from an American base toward the Soviet Union.
Petrov’s job was to report the warning to his supervisors, who would pass the information over to military commanders; those would then consult with the then-Soviet leader, Yuri Andropov, about launching a counterattack.
After minutes of deliberation, he chose not to sound the alarm. “I had a funny feeling in my gut,” he recounted in a 1999 interview. “I didn't want to make a mistake. I made a decision, and that was it.”
It was partly based on the guess that the US would not start a war with just a bunch of missiles, which wouldn’t destroy Soviet defences, and on the fact that ground-based radars showed no evidence of an attack.
An investigation found that the warning was a malfunction caused by satellites misinterpreting the sun’s reflection off the tops of clouds as a missile launch.
A provocative exercise
Another time a nuclear war was averted – which often goes unmentioned – was just weeks later, when NATO launched a massive training exercise codenamed Able Archer.
The Soviet military brass at the time had suspicions that the US might launch a surprise nuclear missile attack, and started an intelligence programme called RYAN to find out if those suspicions were accurate and preempt such an attack.
According to declassified NATO and US Air Force documents, Able Archer, despite being described in 1983 as a “routine” exercise, actually had a number of provocative measures that could have alarmed the Soviet leadership.
Those included a radio-silent air lift of 19,000 US soldiers to Europe, the practice of “new nuclear weapons release procedures,” and numerous international “slips of the tongue” in which B-52 bomber flights were referred to as nuclear “strikes.”
The Soviet military was apparently very concerned about those steps, but “the military officers in charge of the Able Archer exercise minimised this risk by doing nothing in the face of evidence that parts of the Soviet armed forces were moving to an unusual level of alert,” the documents said.
Then-assistant chief of staff for intelligence at US Air Forces Europe, Leonard Perroots, is credited with making the decision not to elevate the alert of the Western command.
One report described Perroots's decision as “fortuitous, if ill-informed” and made “out of instinct, not informed guidance”. However, it still helped quell the danger of Able Archer and avert a meaningless war.