It refers to reign of terror.
(The Reign of Terror, also known as The Terror,
was a period of violence that occurred after the onset of the French
Revolution, incited by conflict between rival political factions, the
Girondins and the Jacobins, and marked by mass executions of "enemies of
the revolution".It began with the overthrow of the Girondins and the ascendancy of the Jacobins under Robespierre.)