 In 1961, Caggiano wrote a prologue for the Spanish translation by Juan Francisco Guevara (who later became a colonel) of "Le Marxisme-léninisme", written by Jean Ousset, private secretary of monarchist intellectual Charles Maurras, and founder of the "Cité catholique" fundamentalist organization.The book states that Marxism–Leninism can be successfully combated only by a "profound faith, an unlimited obedience to the Holy Father, and a thorough knowledge of the Church's doctrines"; and Caggiano thanked the "men of "La Ciudad Católica" of Argentina" for publishing the book.Along with Colonel Jean Gardes, French expert in psychological warfare, Ousset developed the new concept of "subversion".