agent provocateur

Person employed during political or social conflicts, in the guise of an adherent, to stir up compromising action. Agents provocateurs have been used in conflicts throughout history. They are also used in labour disputes to cause or shift the blame for industrial, social, or political unrest.

Agents provocateurs were used by Lord Burghley and Francis Walsingham in Elizabethan England, in France under the ancien régime and the Napoleonic period, in the USA during the Civil War, in Russia before and after the Revolution, and by Germany, Italy, and the USSR in Spain before the outbreak of the Civil War.