High Quality Content by WIKIPEDIA articles! The Reign of Terror (5 September 1793, to 28 July 1794) (the latter is date 10 Thermidor, year II of the French Revolutionary Calendar), also known simply as The Terror (French: la Terreur), 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."