Charlotte was a member of an aristocratic but poor family. She was educated at the Abbaye aux Dames, a convent in Caen, Normandy. She approved of the French revolution, supporting the Girondists.
Jean-Paul Marat (1743 - 1793) was a member of the radical Jacobin faction which initiatied the mass atrocities and beheadings known as the Reign of Terror which followed the early stages of the Revolution. He was a journalist, exerting power through his newspaper, The Friend of the People (L'ami du peuple).
In 1789, when Marat had twenty-two Girondists arrested, Charlotte Corday began to consider killing him. The execution of King Louis XVI (21 January 1793) and the denunciation of Marat by Jacques Pierre Brissot, a leading Girondist, helped her finally decide to do so.
She travelled from Caen to Paris, and stayed at the Hotel de Providence. She bought a table knife at the Palais-Royal, and wrote her Speech to the French who are Friends of Law and Peace, explaining her actions. She went to Marat offering to inform him about a planned Girondist uprising in Caen. She was initially turned away, but on a second attempt Marat admitted her into his presence (he conducted most of his affairs from a bathtub because of a debilitating skin condition).
Marat copied down the names of the Girondists as Corday dictated them to him. She pulled the knife from her scarf and plunged it into his chest, piercing his lung, aorta and left ventricle. He called out, A moi, ma chère amie!, and died.
This is the moment memorialized by Jacques-Louis David's painting The Death of Marat.
At trial, Corday testified that she had carried out the assassination alone. Four days after Marat was killed, she died under the guillotine.
The assassination did not stop the Jacobins or the Terror: Marat became a martyr, and busts of Marat replaced crucifixes and religious statues that were no longer welcome under the new regime.
The enthusiasm for Marat lasted about two years, by which time his actions had been popularly reassessed, and Charlotte re-evaluated as someone who had given her life to rid her country of a monster.