For many years, he immersed himself into history of the Reformation, but only one part of his writings, dealing with the Reformation at Geneva, was published. His Histoire de Marie Stuart (2 vols., 1851) made use of previously unpublished documents from the archives of Simancas. He devoted several volumes to a history of Spain, which had a well-deserved success, including, Charles Quint, son abdication, son séjour et sa mort au monastère de Yuste (1845); Antonio Perez et Philippe II.