[Picture: 19th century painting of the night of 9 Thermidor, espousing National Guardsman Merda's claim of having shot Robespierre]
The Thermidorian Reaction was a revolt in the French Revolution against the excesses of the Reign of Terror.
The Reaction began on July 27, 1794, which the French Republican Calendar dates as 9 Thermidor. Robespierre and Saint-Just came under a concerted and organized attack from other members of the Committee of Public Safety. Robespierre gambled and appealed to the deputies of the Right to support him. However, the deputies of the Right rejected his appeal and the Committee almost unanimously voted against him and his close allies.
The following day, 10 Thermidor (July 28), the new authorities guillotined (without trial, nor even the light formality of a Revolutionary Tribunal) Robespierre, Saint-Just, Georges Couthon, and several other supporters, including members of the Paris Commune (the city government of Paris).
Certainly, the events of 9 Thermidor were to prove a watershed in the revolutionary process. The Thermidorian regime that followed was, at the very least, less rigid, ending the Reign of Terror and allowing for more individual liberty, especially in areas of religion. At the same time, its economic policies paved the way for rampant inflation. Ultimately, power devolved to the hands of the French Directory, an executive of five men who assumed power in France in year III of the French Revolution.
The Convention approved the new "Constitution of the Year III" on 17 August 1795; a plebiscite ratified it in September; and it took effect on 26 September 1795.
The Thermidorian Convention continued until October 26, 1795 (4 Brumaire Year IV), when the National Convention was succeeded by the French Directory.