Several historians consider the "reign of terror" to have begun in 1793, placing the starting date at either 5 September, June or March (birth of the Revolutionary Tribunal), while some consider it to have begun in September 1792 (September Massacres), or even July 1789 (when the first beheadings by guillotine took place), but there is a consensus that it ended with the fall of Robespierre in July 1794.
There was a sense of emergency among leading politicians in France in the summer of 1793 between the widespread civil war and counter-revolution. Mr. Barère exclaimed on 5 September 1793 in the Convention: "Let's make terror the order of the day!" They were determined to avoid street violence such as the September Massacres of 1792 by taking violence into their own hands as an instrument of government.
Robespierre in February 1794 in a speech explained the necessity of terror:
If the basis of popular government in peacetime is virtue, the basis of popular government during a revolution is both virtue and terror; virtue, without which terror is baneful; terror, without which virtue is powerless. Terror is nothing more than speedy, severe and inflexible justice; it is thus an emanation of virtue; it is less a principle in itself, than a consequence of the general principle of democracy, applied to the most pressing needs of the patrie .