Stanislav Petrov died at 77 earlier this year. Why am I remembering him? His incredible discretion and right judgment in an incredible historical moment:

On September 26, 1983, Soviet military officer Stanislav Petrov received a message that five nuclear missiles had been launched by the United States and were heading to Moscow. He didn’t launch a retaliatory strike, believing correctly that it was a false alarm. And with that, he saved the world from nuclear war. …

Karl Schumacher, a political activist in Germany, was one of the first people to publicize Petrov’s story back in the late 1990s. But Schumacher reportedly learned of Petrov’s death this month after contacting Petrov’s home. Petrov’s son Dmitry reported that the man who saved the world all those years ago had died on May 19, 2017.

How many heroes live among us, living quiet lives after their moment of proving has come and gone? No doubt this man was one of the least known heroes of the Cold War, but he was one of many who stopped nuclear war:

Lt. Col. Stanislav Petrov was 44 years old and working at a missile detection bunker south of Moscow on September 26, 1983. His computer told him that five nuclear missiles were on their way, and given their flight time, he had just 20 minutes to launch a counter attack. But Petrov told his superior officers that it was a false alarm. He had absolutely no real evidence that this was true, but it probably saved millions of lives.

“The siren howled, but I just sat there for a few seconds, staring at the big, back-lit, red screen with the word ‘launch’ on it,” Petrov told the BBC’s Russian Service back in 2013.

“I had all the data [to suggest there was an ongoing missile attack]. If I had sent my report up the chain of command, nobody would have said a word against it,” Petrov said.

“There was no rule about how long we were allowed to think before we reported a strike. But we knew that every second of procrastination took away valuable time; that the Soviet Union’s military and political leadership needed to be informed without delay,” he told the BBC. …

Perhaps importantly, Petrov noted that he was the only officer around that day who had received a civilian education. Everyone else were professional soldiers and he believed that they would have simply reported the attack at face value. The men around him were “taught to give and obey orders.” Luckily, Petrov disobeyed what simply didn’t feel right to him.

Petrov reasoned that if the Americans were going to launch a first strike they’d send more than five missiles, despite the fact that they could still do an enormous amount of damage. He also believed that since the alert system was relatively new it seemed likely that it could be sending a false alarm.

If Petrov had been wrong, he would have compromised the Soviet Union’s ability to retaliate against a nuclear strike. But if he was right, World War III would be averted. Thankfully, he was right.