This sounds like the concept of the motivated sequence (take public speaking, folks) where the speaker inspires the audience to take action, and I think this concept is brilliantly illustrated in Mark Antony's speech from William Shakespeare's Julius Caesar. This brief clip from the Mankiewicz film demonstrates how Mark Antony provokes a unique passion from his audience that directly leads to action - the chaos that consumes Rome in the second half of the play/film. There a plenty of examples of this motivated sequence from pop culture, but Shakespeare/Mankiewicz/Brando illustrate it brilliantly.