A great unsolved mystery in American political culture is what became of the U.S. Congress's state portraits of Louis XVI and Marie-Antoinette during the British invasion of the Capitol, Wash., D.C., on the night of 24-25 August 1814. These were official full length images of the French monarchs arrayed in ceremonial magnificence. The fate of the royal portraits has been difficult to determine. Larkin undertakes a comprehensive examination to test two theories -- that the royal portraits were burned by British troops during their occupation of the capital or looted by American scavengers during the chaotic aftermath. He breaks new ground for the creating of an art and material history for the War of 1812. Illus.