In Chapter 15 of To Kill a Mockingbird, who caused the mob outside of the jail to break up?

In Chapter 15, the Old Sarum bunch arrives at the Maycomb County jail to harm Tom Robinson. However, Atticus is sitting outside of Tom's jail cell keeping watch. Walter Cunningham is the leader of the mob, and he tells Atticus that he needs to "get aside from the door." (Lee 202) Unbeknownst to Atticus, his children are discreetly standing close by. Suddenly, Scout runs into the group of men circled around Atticus. Scout, unaware of the precarious situation her father is in, spots Walter Cunningham. She attempts to make short conversation with Walter by mentioning her friendship with his son, Walter Cunningham Jr., as well as his "entailment." Everyone standing in the group, including Atticus, is awestruck by Scout's appearance and her casual demeanor.

Scout's arrival and courteous conversation eventually grab the attention of Walter Cunningham, who tells the mob to leave. The next day, Atticus tells Scout that her presence made Walter Cunningham stand in Atticus' shoes for a minute. (Lee 210) Walter Cunningham was able to view the events through Atticus' perspective and made the moral choice to leave. Scout is responsible for "breaking" the mob up, outside of the jail.