|Servant of God|
|Founder, Legion of Mary|
Francis Michael Duff|
7 June 1889
7 November 1980 (aged 91)|
|Venerated in||Roman Catholic Church, especially by the Legion of Mary|
Servant of God Francis Michael "Frank" Duff (7 June 1889 – 7 November 1980) is known especially for bringing attention to the role of the laity during the Second Vatican Council of the Roman Catholic Church as well as for founding the Legion of Mary in his native city of Dublin, Ireland.
He was born in Dublin on 7 June 1889, the eldest of seven children of John Duff (died 23 December 1918) and his wife, Susan Letitia (née Freehill, died 27 February 1950). The wealthy family lived in the city at St Patrick's Road, Drumcondra.
Duff attended Blackrock College.
Six years later, he joined the Society of St Vincent de Paul and was exposed to the real poverty of Dublin. Many who lived in tenement squalor were forced to attend soup kitchens for sustenance, and some of the natural consequences of abject poverty, alcoholism and prostitution were rife in Dublin. Duff joined and soon rose through the ranks to President of the St Patrick's Conference at St Nicholas of Myra Parish. Duff, having concern for people he saw as materially and spiritually deprived, got the idea to picket Protestant soup kitchens as they were giving aid in the form of food and free accommodation at hostels for not attending Catholic services. Duff set up rival Catholic soup kitchens and, with his friend Sergeant Major Joe Gabbett, who had already been working at discouraging Catholics from patronizing Protestant soup kitchens, succeeded in closing down two of them over the years. 
In 1916, Duff published his first pamphlet, Can we be Saints?. In it, he expressed the conviction that all, without exception, are called to be saints, and that through Christian faith, all have the means necessary.
He briefly acted as private secretary to Michael Collins, the chairman of the Provisional Government and the commander-in-chief of the National Army. In 1924, he was transferred to the Department of Finance.
Legion of Mary
Inspired by St. Louis de Montfort's True Devotion to Mary, he founded the Legion of Mary. Along with a group of Catholic women as well as Michael Toher, a priest of the Dublin Archdiocese, Duff formed the first branch of what was to become the first praesidium of the Legion of Mary on 7 September 1921.
For the rest of his life, with the help of many others, he guided the Legion's extension worldwide extension.
The Legion of Mary is a lay apostolate organisation at the service of the Roman Catholic Church, under ecclesiastical guidance. Its twofold purpose is the spiritual development of its members and the advancement the reign of Christ through Mary. The first legionairies were women. Today, the Legion of Mary has an estimated four million active members and 10 million auxiliary members in close to 200 countries in almost every diocese in the Catholic Church.
In 1965, Pope Paul VI invited Duff to attend the Second Vatican Council as a lay ovserver. Duff made promotion of devotion to the Sacred Heart of Jesus part of the Legion's apostolacy. He took to heart the words of Our Lord to Saint Margaret Mary Alacoque: "My Heart is so inflamed with Love for men that it is no longer able to keep within itself the flames of its burning Love. It must make itself known unto men to enrich them with the treasures it contains".
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".
- Burns, J.S. (1956). "Walking with Mary (The spirit of the Legion of Mary". Glasgow. ASIN B0007IXKU2.
- Radio documentary, 26 June 2011, on Duff's life http://www.rte.ie/radio1/bowmansundaymorning]
- Drake, Tim."Frank Duff: A New Evangelist Ahead of His Time", catholicpulse.com, 1 April 2014.
- Kennedy, Finola. Frank Duff: A Life Story, Bloomsbury Publishing, 2011; ISBN 978-08264-432-50.
- The biography of Frank Duff, on the website of the Center for the Promotion of Legion of Mary Saints; retrieved 18 March 2007.
- Frank Duff - A Living Autobiography by Monsignor Charles T. Moss, Maria Legionis, 1983, p. 20-22
- Kennedy, Finola (2007). Frank Duff: A Life Story. Burns & Oates. ISBN 978-14411-674-77.,
- Cooney, John (1 January 1999). "John Charles McQuaid: Ruler of Catholic Ireland". Syracuse University Press. Retrieved 19 February 2017 – via Google Books.
- Molloy, Cian."Sainthood Cause Delayed for Legion of Mary Founder", National Catholic Register, 8 February 1998.
- Cooney, John. "Review: Biography: 'Frank Duff, A Life Story' by Finola Kennedy", independent.ie, 23 July 2011, accessed 19 September 2014.
- Legion of Mary official website Archived 13 August 2006 at the Wayback Machine., legion-of-mary.ie; accessed 1 August 2015.
- Kennedy, Finola (2007). Frank Duff: A Life Story. Burns & Oates. ISBN 978-1441167477.
- Moss, Monsignor Charles T. (1983). Frank Duff - A Living Autobography. Legion of Mary.