In Rome, the First Senator is addressing the tribunes, officers chosen by the people to protect their liberties against the Senate. The Senator announces that Augustus Caesar has decided that the forces now in Gallia are too weak to take on the rebellious Britons. Therefore, the gentry-the land-owning class of people below the nobility-are called to this job. The tribunes must see that this happens. Caesar has made Lucius proconsul and general of the forces.
This scene is often cut and it is doubtful whether Shakespeare wrote it. It serves no dramatic purpose except to remind us of the forthcoming Roman invasion of Britain. It may have been interpolated because of staging requirements.
Cymbeline: Novel Summary: Act 3 Scene 8