 Lefebvre became concerned about the direction the Council 's deliberations were taking , taking a leading part in a study group of bishops at the Council which became known as the Coetus Internationalis Patrum ( International Group of Fathers ) , with other traditional @-@ leaning bishops Antônio de Castro Mayer , Bishop of Campos and Geraldo de Proença <unk> , Archbishop of Diamantina . 
