The young girl responds by kicking the hostile man.  As she looks around her, though, she finally sees a familiar face among the mob, Mr. Walter Cunningham, a former client of Atticus’ law practice.  Scout calculates, correctly, that if she can make common cause with this one individual, it will help to quell the angry mob that surrounds her and that threatens her father.  Calling out to Mr. Cunningham with a friendly greeting, Scout initially feels that her gambit is failing, even when she informs Cunningham that his son is her classmate and that he is a good kid.  She also appeals to his association with her father, mentioning “entailments.”  As described in the following passage, Scout’s tactics begin to bear fruit:

“Atticus had said it was the polite thing to talk to people about what they were interested in, not about what you were interested in. Mr. Cunningham displayed no interest in his son, so I tackled his entailment once more in a last-ditch effort to make him feel at home. ‘Entailments are bad,’ I was advising him, when I slowly awoke to the fact that I was addressing the entire aggregation. The men were all looking at me, some had their mouths half-open. Atticus had stopped poking at Jem: they were standing together beside Dill. Their attention amounted to fascination.”

Having succeeded in diverted the mob’s attention, Scout has prevailed in defusing the tension. Mr. Cunningham, having been confronted by this small girl, has lost his capacity for violence.  Responding suddenly to Scout’s previous request that he give her regards to his son, Mr. Cunningham ends the confrontation with Atticus:

“Atticus said nothing. I looked around and up at Mr. Cunningham, whose face was equally impassive. 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. Then he straightened up and waved a big paw. “Let’s clear out,” he called. ‘Let’s get going, boys.’”

Mr. Cunningham, the one member of the mob who resided within this community, was the apparent leader.  By appealing to his sense of decency, Scout caused him to calm down and regain a sense of perspective.  She succeeded in humanizing the situation at a time when these hostile, potentially violent intruders were intent on seizing and murdering a man they viewed as an inferior being.  Scout diverted their attention away from their mission and towards herself and, in so doing, injected the innocence of a small child into the atmosphere. The key, however, lay in her ability to appeal to Mr. Cunningham’s sense of decency.  Once she had accomplished that, he was no longer of a mind to instigate a riot and a murder.  Once the leader of the mob had been essentially defused, the rest were content to forget their plans and go on home.  Kill the head, and the body will die, as the saying goes.  Mr. Cunningham was the head. The rest of the mob was the body. Once he had been contained, the rest were helpless.

Atticus says that Scout helped the mob come to its senses by reminding them that they were human.

Atticus knows that many of the people of Maycomb do not approve of him defending Tom Robinson.  To them, Robinson is a black man who raped a white girl, and presumed guilty.

A group of men, including Walter Cunningham, Sr., gathers around Tom Robinson’s cell one night.  Atticus knew they would be there, and set up a chair and a lamp outside Robinson’s door.

Scout, Dill, and Jem found out where Atticus was, and came down to see what was going on. Scout did not realize the significance of the mob.  She felt that the situation was awkward, and tried to drum up a conversation with Cunningham because she was friends with his son.

"Entailments are bad," I was advising him, when I slowly awoke to the fact that I was addressing the entire aggregation. The men were all looking at me, some had their mouths half-open…. (Ch 15)

Cunningham is embarrassed and confused, and leaves—taking the mob with him.  Atticus tells Jem that they would not have killed him because a mob is “always made up of people, no matter what” (ch 16).  He chuckles to state that what reminded them of this was Scout talking to Walter.

"That proves something- that a gang of wild animals can be stopped, simply because they're still human….” (ch 16)

This incident demonstrates that no matter what happens, the people of Maycomb are still friends and neighbors.  Tensions are high, but they have to stick together no matter what.  It took Scout’s innocent intervention to remind Walter Cunningham of that.

In To Kill a Mockingbird, the mob is brought to its senses somewhat by Scout recognizing one of the members of the mob and asking about that person's child. This sort of thing takes the anonymity out of the mob atmosphere. Recognition is identification. Once a member of the mob is made human again by simple recognition, the mob atmosphere is broken.

After that scary scene in chapter 15, Atticus sits down with the children in chapter 16 and explains what happened.  Scout made Mr. Cunningham stand in Atticus' shoes that night in front of the jailhouse.  Walter has children of his own, and Scout made him realize that he wouldn't want his children in a situation like that, either.  Atticus says,

"'Mr. Cunningham was part of that mob last night, but he was still a man.  Every mob in every Southern town is always made up of people you know.  So it took an eight-year-old child to bring 'em to their senses, didn't it?'"