 Ordained a diocesan priest in 1929, he had joined the Holy Ghost Fathers for missionary work and was assigned to teach at a seminary in Gabon in 1932.In 1947, he was appointed Vicar Apostolic of Dakar, Senegal, and the next year as the Apostolic Delegate for West Africa.Upon his return to Europe he was elected Superior General of the Holy Ghost Fathers and assigned to participate in the drafting and preparation of documents for the upcoming Second Vatican Council (1962–1965) announced by Pope John XXIII, and was a major leader of the conservative bloc during its proceedings.