As Atticus explained to the children later, a mob is not a single entity but is always made up of men, and usually "people you know." Scout recognized one of the men as Mr. Cunningham, who she knew Atticus had once represented and who was the father of her friend, Walter Jr. She politely said hello, and began a conversation with him, not knowing that Cunningham and his friends had murder on their minds. Her sincere concern for Cunningham's "entailment" issues and her kind words about Walter Jr. shamed the man, and
Then he did a peculiar thing. He squatted down and took me by both shoulders.
"I'll tell him you said hey, little lady," he said.
Cunningham ordered his companions to "Let's get going, boys," and the potentially deadly situation dissolved.
"... it took an eight-year-old child to bring 'em to their senses, didn't it?" said Atticus. "That proves something--that a gang of wild animals can be stopped, simply because their still humans."