Chamberlain was trying to avert world war, and it seemed to him that he would benefit from taking the measure of Hitler for himself. Was Hitler someone who could be reasoned with? Trusted? Chamberlain wanted to find out.

On the morning of September 14, the British ambassador to Germany sent a telegram to Hitler’s foreign minister, Joachim von Ribbentrop. Would Hitler like to meet? Von Ribbentrop replied the same day: yes.

Chamberlain was a masterly politician with a gift for showmanship, and he artfully let the news slip. He was going to Germany to see if he could avert war. Across Britain, there was a shout of celebration. Polls showed that 70 percent of the country thought his trip was a “good thing for peace.”

The newspapers backed him. In Berlin, one foreign correspondent reported that he had been eating in a restaurant when the news broke, and the room had risen, as one, to toast Chamberlain’s health.

Chamberlain left London on the morning of September 15. He’d never flown before, but he remained calm even as the plane flew into heavy weather near Munich. Thousands had gathered at the airport to greet him. He was driven to the train station in a cavalcade of fourteen Mercedes, then had lunch in Hitler’s own dining car as the train made its way into the mountains, toward Hitler’s retreat at Berchtesgaden.

He arrived at five in the evening. Hitler came and shook his hand. Chamberlain would later report every detail of his first impressions in a letter to his sister Ida:

“Halfway down the steps stood the Führer bareheaded and dressed in a khaki-coloured coat of broadcloth with a red armlet and a swastika on it and the military cross on his breast. He wore black trousers such as we wear in the evening and black patent leather lace-up shoes. His hair is brown, not black, his eyes blue, his expression rather disagreeable, especially in repose and altogether he looks entirely undistinguished. You would never notice him in a crowd and would take him for the house painter he was.”

Hitler ushered Chamberlain upstairs to his study, with just an interpreter in tow. They talked, sometimes heatedly. “I am ready to face a world war!” Hitler exclaimed to Chamberlain at one point. Hitler made it plain that he was going to seize the Sudetenland, regardless of what the world thought.

Chamberlain wanted to know whether that was all Hitler wanted. Hitler said it was. Chamberlain looked at Hitler long and hard and decided he believed him. In the same letter to his sister, Chamberlain wrote that he had heard back from people close to Hitler that the German leader felt he had had a conversation “with a man.” Chamberlain went on:

“In short I had established a certain confidence which was my aim, and on my side in spite of the hardness and ruthlessness I thought I saw in his face I got the impression that here was a man who could be relied upon when he had given his word.”

Chamberlain flew back to England the next morning. At Heston Airport, he gave a quick speech on the tarmac. “Yesterday afternoon I had a long talk with Herr Hitler,” he said. “I feel satisfied now that each of us fully understands what is in the mind of the other.”

The two of them would meet again, he promised, only this time closer to England. “That is to spare an old man such another long journey,” Chamberlain said, to what those present remembered as “laughter and cheers.”

Chamberlain’s negotiations with Hitler are widely regarded as one of the great follies of the Second World War. Chamberlain fell under Hitler’s spell. He was outmaneuvered at the bargaining table. He misread Hitler’s intentions, and failed to warn Hitler that if he reneged on his promises there would be serious consequences. History has not been kind to Neville Chamberlain.

But underneath those criticisms is a puzzle. Chamberlain flew back to Germany two more times. He sat with Hitler for hours. The two men talked, argued, ate together, walked around together. Chamberlain was the only Allied leader of that period to spend any significant time with Hitler. He made careful note of the man’s behaviour.

“Hitler’s appearance and manner when I saw him appeared to show that the storm signals were up,” Chamberlain told his sister Hilda after another of his visits to Germany. But then “he gave me the double handshake that he reserves for specially friendly demonstrations.”

Back in London, he told his cabinet that he had seen in the Führer “no signs of insanity but many of excitement.” Hitler wasn’t crazy. He was rational, determined: “He had thought out what he wanted and he meant to get it and he would not brook opposition beyond a certain point.”

Chamberlain was acting on the same assumption that we all follow in our efforts to make sense of strangers. We believe that the information gathered from a personal interaction is uniquely valuable.

You would never hire a babysitter for your children without meeting that person first. Companies don’t hire employees blind. They call them in and interview them closely, sometimes for hours at a stretch, on more than one occasion.

They do what Chamberlain did: they look people in the eye, observe their demeanour and behaviour, and draw conclusions. He gave me the double handshake. Yet all that extra information Chamberlain gathered from his personal interactions with Hitler didn’t help him see Hitler more clearly. It did the opposite.

Is this because Chamberlain was naive? Perhaps. His experience in foreign affairs was minimal. One of his critics would later compare him to a priest entering a pub for the first time, blind to the difference “between a social gathering and a rough house.”

Excerpted with permission from Talking To Strangers: What We Should Know About The People We Don’t Know, Malcolm Gladwell, Allen Lane.