The Coetus Internationalis Patrum (Latin for International Group of Fathers) was a study group of the conservative-minded bishops at the Second Vatican Council. The members included prelates such as Cardinals Francis Spellman, Alfredo Ottaviani, Archbishop Marcel Lefebvre, and Bishops Casimiro Morcillo of Madrid, Antônio de Castro Mayer of Campos and Geraldo de Proença Sigaud of Diamantina.