Final answer:
Cinna the poet is mistaken for Cinna the conspirator and is violently attacked by a mob before they leave him.
Step-by-step explanation:
Before the mob leaves Cinna in Act 3, Scene 3 of Shakespeare's Julius Caesar, they mistake him for Cinna the conspirator against Julius Caesar, when in fact he is Cinna the poet. Due to this case of mistaken identity, Cinna is subjected to a violent confrontation by the mob, which is incensed and eager to take out their anger on any perceived supporter of Caesar's assassination. Despite Cinna's attempts to clarify that he is not the conspirator, the enraged mob does not listen and continues to attack him before eventually leaving him.