Augustin-Louis, Baron Cauchy (1789-1857) was the pre-eminent French mathematician of the nineteenth century. He began his career as a military engineer during the Napoleonic Wars, but even then was publishing significant mathematical papers, and was persuaded by Lagrange and Laplace to devote himself entirely to mathematics. His greatest contributions are considered to be the Cours d'analyse de l'Ecole Royale Polytechnique (1821), Resume des lecons sur le calcul infinitesimal (1823) and Lecons sur les applications du calcul infinitesimal a la geometrie (1826-8), and his pioneering work encompassed a huge range of topics, most significantly real analysis, the theory of functions of a complex variable, and theoretical mechanics. Twenty-six volumes of his collected papers were published between 1882 and 1958. The first series (volumes 1-12) consists of papers published by the Academie des Sciences de l'Institut de France; the second series (volumes 13-26) of papers published elsewhere.