The Man in the Iron Mask was an unidentified prisoner of state during the reign of Louis XIV of France (1643–1715). The strict measures taken to keep his imprisonment secret resulted in a long-lasting legend about his identity. Warranted for arrest on 19 July 1669 under the name of "Eustache Dauger", he was apprehended near Calais on 28 July, incarcerated on 24 August, and held for 34 years in the custody of Bénigne Dauvergne de Saint-Mars in four successive French prisons, including the Bastille. He died there on 19 November 1703, and his burial certificate bore the name of "Marchioly", leading several historians to conclude that the prisoner was Italian diplomat Ercole Antonio Mattioli.

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