See A. Soboul, The Sans-cullotes (1981).
Sans-culottes (French for "without knee-breeches") was a term created around 1790 - 1792 by the French aristocracy to describe the poorer members of the Third Estate, according to the dominant theory because they usually wore pantaloons (full-length trousers or pants) instead of the silk knee-breeches then in fashion. The term came to refer to the ill-clad and ill-equipped volunteers of the Revolutionary army during the early years of the French Revolutionary Wars, but, above all, to the working class radicals of the Revolution. From this comes the now slightly archaic term sansculottism or sans-culottism, meaning extreme egalitarian republican principles.
The sans-culottes were for the most part members of the poorer classes, or leaders of the populace, but during the Reign of Terror, public functionaries and persons of good education styled themselves citoyens sans-culottes.
The distinctive costume of typical sans-culottes featured:
Their support came from domestic crises, such as shortages of bread and political injustices. Led by revolutionaries such as Jacques Hébert, the sans-culottes played a crucial role in such events as the September massacres of 1792, and supported the most radical left-wing factions in successive revolutionary governments. During the Reign of Terror, they provided important support for Maximilien Robespierre and the Committee of Public Safety; in March 1794, though, the government distanced itself from the Hébertists; Hébert himself was convicted by the very Revolutionary Tribunals he had lauded, and was guillotined; months later, in the Thermidorian Reaction, Robespierre would suffer the same fate.
The influence of the sans-culottes ceased with the reaction that followed the fall of Robespierre (July 1794), and the name itself became proscribed. Without effective leadership of their own, and no longer allied with the Jacobins, the sans-culottes largely ceased to be a major factor in French politics.