Francis Michael "Frank" Duff KC*SG (7 June 1889 – 7 November 1980) was born in Dublin, the eldest of seven children of John and Susan (née Freehill) Duff. On leaving Blackrock College, he entered the Civil Service at age 18. Six years later he joined the Society of St. Vincent de Paul, and witnessed at first hand the real poverty of Dublin of that time. In 1916 he published his first pamphlet: 'Can we be Saints?', in which he expressed the conviction that all without exception are called to be saints, and that through Christian faith all persons have available the means necessary to attain such sainthood. In 1917 he was influenced deeply by St. Louis de Montfort’s treatise: 'True Devotion to Mary', which instilled a deep spiritual faith in Mary. Along with a group of Catholic women and Fr. Michael Toher, a priest of the Dublin Archdiocese, he formed the first branch of what was to become the first praesidium of the Legion of Mary, on 7 September 1921. For the remainder of his life he guided the world-wide extension of the Legion with the spiritual development of its members and advancing the reign of Christ through Mary as its twofold purpose. He also advocated devotion to the Sacred Heart of Jesus a part of the Legion Apostolate. Today between active and auxiliary (praying) members there are reportedly in excess of 10,000,000 members worldwide. In 1965, Pope Paul VI invited Frank Duff to attend the Second Vatican Council as a Lay Observer, an honour by which the Pope recognised and affirmed Duff's work for the lay apostolate. Frank Duff wrote the following prayer: "O Lord, all hearts are in Your Hand. You can bend as it pleases You the most obdurate and soften the most hardened. Do that honour this night through the Blood, merits, wounds, names and inflamed Hearts of Your Beloved Son and His Most Holy Mother by granting the conversion of the whole world. Nothing less My God, Nothing less because of Mary Thy Mother and because of Thy might and Thy Mercy". On 7 November 1980, Frank Duff died at the age of 91 and was interred in Glasnevin Cemetery, Dublin. In July 1996 the Cause of Frank Duff's canonisation was introduced by the then Archbishop of Dublin, Cardinal Desmond Connell. A prayer for his canonisation: God our Father, You inspired your servant Frank Duff with a profound insight into the mystery of Your Church, the Body of Christ, and of the place of Mary the Mother of Jesus in this mystery. In his immense desire to share this insight with others and in filial dependence on Mary he formed her Legion to be a sign of her maternal love for the world and a means of enlisting all her children in the Church's evangelising work. We thank you Father for the graces conferred on him and for the benefits accruing to the Church from his courageous and shining faith. With confidence we beg You that through his intercession you grant the petition we lay before You . ..... We ask too that if it be in accordance with Your will, the holiness of his life may be acknowledged by the Church for the glory of your Name, through Christ Our Lord Amen.
Frank Duff was named a Servant of God.