During 1794, the revolutionary government of France was threatened by internal enemies, conspirators, and foreign monarchies. Within France the revolution was opposed by the former French nobility, which had lost its inherited privileges. The Roman Catholic Church was generally against the Revolution, which had turned the clergy into employees of the state and required they take an oath of loyalty to the nation (through the Civil Constitution of the Clergy). In addition, the First French Republic was engaged in a series of French Revolutionary Wars with neighboring powers. European monarchies wanted to stifle the democratic and republican ideals that might threaten their own stability.
The extension of civil war and the advance of foreign armies on national territory produced a political crisis, and increased the rivalry between the Girondins and the more radical Jacobins; the latter were eventually grouped in the parliamentary faction called the Mountain, and had the support of the Parisian population. The French government established the Committee of Public Safety, which took its final form on 6 September 1793 and was ultimately dominated by Maximilien Robespierre, in order to suppress internal counter-revolutionary activities and raise additional French military force. Through the Revolutionary Tribunal, the Terror's leaders exercised broad dictatorial powers and used them to instigate mass executions and political purges. The repression accelerated in June and July 1794, a period called "la Grande Terreur" (The Great Terror), and ended in the "Thermidorian Reaction," or coup of 9 Thermidor Year II (27 July 1794), in which several leaders of the Reign of Terror were executed, including Louis de Saint-Just and Robespierre.
On 2 June Paris sections — encouraged by the enragés ("enraged ones") Jacques Roux and Jacques Hébert — took over the Convention, calling for administrative and political purges, a low fixed price for bread, and a limitation of the electoral franchise to sans-culottes alone. With the backing of the National Guard, they convinced the Convention to arrest 31 Girondin leaders, including Jacques Pierre Brissot. Following these arrests, the Jacobins gained control of the Committee of Public Safety on 10 June, installing the revolutionary dictatorship. On 13 July the assassination of Jean-Paul Marat — a Jacobin leader and journalist known for his bloodthirsty rhetoric — by Charlotte Corday, a Girondin, resulted in further increase of Jacobin political influence. Georges Danton, the leader of the August 1792 uprising against the King, was removed from the Committee. On 27 July Robespierre, self-styled as "the Incorruptible", made his entrance, quickly becoming the most influential member of the Committee as it moved to take radical measures against the Revolution's domestic and foreign enemies.
Meanwhile, on 24 June the Convention adopted the first republican constitution of France, the French Constitution of 1793. It was ratified by public referendum, but never put into force; like other laws, it was indefinitely suspended by the decree of October that the government of France would be "revolutionary until the peace". The eventual constitution under the Directory was quite different.
Facing local revolts and foreign invasions in both the East and West of the country, the most urgent government business was the war. On 17 August the Convention voted for general conscription, the levée en masse, which mobilized all citizens to serve as soldiers or suppliers in the war effort. On 5 September the Convention institutionalized The Terror: systematic and lethal repression of perceived enemies within the country.
On 25 December 1793 Robespierre stated:
The goal of the constitutional government is to conserve the Republic; the aim of the revolutionary government is to found it... The revolutionary government owes to the good citizen all the protection of the nation; it owes nothing to the Enemies of the People but death.. These notions would be enough to explain the origin and the nature of laws that we call revolutionary ... If the revolutionary government must be more active in its march and more free in his movements than an ordinary government, is it for that less fair and legitimate? No; it is supported by the most holy of all laws: the Salvation of the People.
On 5 February 1794 he stated, more succinctly:
La terreur n'est autre chose que la justice prompte, sévère, inflexible.'' ("Terror is nothing other than prompt, severe, inflexible justice.")
The result was policy through which the state used violent repression to crush resistance to the government. Under control of the effectively dictatorial Committee, the Convention quickly enacted more legislation. On 9 September the Convention established sans-culottes paramilitary forces, the revolutionary armies, to force farmers to surrender grain demanded by the government. On 17 September the Law of Suspects was passed, which authorized the charging of counter-revolutionaries with vaguely defined crimes against liberty. On 29 September the Convention extended price-fixing from grain and bread to other essential goods, and also fixed wages. The guillotine became the symbol of a string of executions: Louis XVI had already been guillotined before the start of the terror; Marie-Antoinette, the Girondins, Philippe Égalité, Madame Roland and many others lost their lives under its blade. The Revolutionary Tribunal summarily condemned thousands of people to death by the guillotine, while mobs beat other victims to death. Sometimes people died for their political opinions or actions, but many for little reason beyond mere suspicion, or because some others had a stake in getting rid of them. Most of the victims received an unceremonious trip to the guillotine in an open wooden cart (the tumbrel). Loaded onto these carts, the victims would proceed through throngs of jeering men and women.
The victims of the Reign of Terror totaled approximately 40,000. Among people who were condemned by the revolutionary tribunals, about 8 percent were aristocrats, 6 percent clergy, 14 percent middle class, and 70 percent were workers or peasants accused of hoarding, evading the draft, desertion, rebellion, and other purported crimes. Of these social groupings, the clergy of the Roman Catholic church suffered proportionately the greatest loss.
Another anti-clerical uprising was made possible by the installment of the Revolutionary Calendar on 24 October. Against Robespierre's concepts of Deism and Virtue, Hébert's (and Chaumette's) atheist movement initiated a religious campaign in order to dechristianize society. The program of dechristianization waged against Catholicism, and eventually against all forms of Christianity, included the deportation of clergy and the condemnation of many of them to death, the closing of churches, the institution of revolutionary and civic cults, the large scale destruction of religious monuments, the outlawing of public and private worship and religious education, forced marriages of the clergy and forced abjurement of their priesthood. The enactment of a law on 21 October 1793 made all suspected priests and all persons who harbored them liable to death on sight. The climax was reached with the celebration of the goddess "Reason" in Notre Dame Cathedral on 10 November. Because dissent was now regarded as counterrevolutionary, extremist enragés such as Hébert and moderate Montagnard indulgents such as Danton were guillotined in the Spring of 1794. On 7 June Robespierre, who had previously condemned the Cult of Reason, advocated a new state religion and recommended that the Convention acknowledge the existence of God. On the next day, the worship of the deistic Supreme Being was inaugurated as an official aspect of the Revolution. Compared with Hébert's somewhat popular festivals, this austere new religion of Virtue was received with signs of hostility by the Parisian public.
The fall of Robespierre had been brought about by a combination of those who wanted more power for the Committee of Public Safety, and a more radical policy than he was willing to allow, with the moderates who opposed the Revolutionary Government altogether. They had, between them, made the Law of 22 Prairial one of the charges against him, and after his fall, advocating Terror would mean adopting the policy of a convicted enemy of the Republic, endangering the advocate's own head.
The reign of the standing Committee of Public Safety was ended. New members were appointed the day after Robespierre's execution, and term limits were imposed (a quarter of the committee retired every three months); its powers were reduced piece by piece. This was not an entirely or immediately conservative period; no government of the Republic envisaged a Restoration, and Marat was reburied in the Pantheon in September, although he had been more extreme than Robespierre. But politicians united in opposing the Jacobins, and the period has become known as the Thermidorian Reaction.