Duff, Francis Michael (‘Frank’) (1889–1980), founder of the Legion of Mary, was born 7 June 1889 in Dublin, elder son among two sons and five daughters of John Duff, a civil servant with the local government board, and Susan Letitia Duff (née Freehill), a civil servant with the post office. After an initial education in a dame school, he entered Blackrock College (1899). In his final year (1907) he was awarded a first-class exhibition, valued at £40, in the modern literary course, but the need to support his family after his father took early retirement (1903) prevented him from embarking on university studies. A moderate nationalist, he passed a second-division civil service examination in 1908 and was assigned to the land commission, where he developed a novel methodology in regard to the calculation of land annuities. At the age of 21 (1911) he was invited to the treasury in London to discuss his method. After the treaty he transferred to the Irish civil service, and from January 1922 to December 1923 he worked directly to Patrick Hogan (qv), minister for agriculture, on the Land Act, 1923. In January 1924 he transferred to the Department of Finance, where he remained until he took early retirement on 1 October 1934 under the Civil Service (Transferred Officers) Compensation Act, 1929. His younger brother, John (1895–1949), who also joined the civil service, became secretary of the Department of Justice in 1949.
Although Frank Duff initially showed few overt signs of religious activism, in 1913 he was introduced into the Society of St Vincent de Paul. Gradually he turned more and more in the direction of religious practice and service of his fellow man. In 1918 a friend gave him a copy of Treatise on true devotion to the Blessed Virgin by the seventeenth-century French cleric Grignion de Montfort, which led him to an appreciation of the role of Mary. John Henry Newman (qv) – of whom Duff wrote: ‘I have always been profoundly affected throughout my life by the writings of Newman’ (Duff to Fr Flood, 11 May 1976; archives of the Concilium of the Legion of Mary) – was another source of inspiration, especially in relation to the role of the laity and the role of Mary. On 7 September 1921, along with Fr Michael Toher and fifteen women, predominantly young, he was present at the first meeting of the association which he would forge as the Legion of Mary. Duff modelled the Legion on the Roman army, naming the local unit the ‘praesidium’, and he immersed himself in the apostolic work which dominated the rest of his life. The Legion tried to tackle pressing social problems such as homelessness and prostitution, and was underpinned by Duff's belief in a ‘hands-on’ approach and his insistence that religious faith was not in itself sufficient but needed to be translated into practice across class barriers. In 1922 he established the Sancta Maria hostel in Dublin as a refuge for prostitutes, and was the driving force behind the closure of ‘Monto’, Dublin's notorious red-light district. In 1927 he established the Morning Star hostel for homeless men in Dublin, and in 1930 the Regina Coeli hostel for homeless women, which provided special units for unmarried mothers and their children at a time when neither church nor state favoured helping unmarried women to keep their children.
Although he was supported in his charitable endeavours by W. T. Cosgrave (qv), who facilitated the provision of hostel premises and arranged a meeting with Pope Pius XI in May 1931, Duff's early apostolic initiatives were not welcomed by the Dublin diocesan authorities. The result was that formal episcopal approval of the Legion in the Dublin archdiocese was withheld until 1935. Two successive archbishops of Dublin, Edward Joseph Byrne (qv) and John Charles McQuaid (qv), sought to censor Duff's activities and publications, particularly the Legion's accounts of its work with prostitutes. A typical example was the restriction placed in late 1942 by Archbishop McQuaid on the Mercier Society (a discussion group for mutual understanding, formed by Duff and involving a joint committee of catholics and protestants), leading to its suspension in 1944. A similar fate attended the Pillar of Fire Society for dialogue with the Jewish community. In discussion with leading literary dissidents such as Sean O'Faolain (qv) and Peadar O'Donnell (qv), Duff suggested that their battles with catholic censors were nothing compared with his own.
Nonetheless, with the support of Cardinal Joseph MacRory (qv), and Cardinal Bourne of Westminster, the Legion flourished both at home and abroad (c.2000 the membership was 3.5 million worldwide). In 1928 the first praesidium outside Ireland was established in Scotland. At the time of the eucharistic congress in Dublin in 1932, many visiting bishops encountered the Legion of Mary for the first time and brought it back to their dioceses. In 1934 the first Legion envoy, Mary Duffy, departed for the US and Canada. Others followed her example to the four corners of the globe, most notably Edel Quinn (qv) to Africa and Alfie Lambe to South America. In 1947 Fr Aedan McGrath (qv) was appointed to extend the Legion in China. The Legion owed its growth partly to Duff's disciplinary approach and to his success in presenting catholic apostolic activity as an intrinsic part of putting the faith of the ordinary catholic into practice.
Duff had no specialised or academic theological training, but wrote extensively and in an accessible manner on the doctrines of the church – in particular, on the church as the mystical body of Christ and on the role of Mary. His major publication, the Handbook of the Legion of Mary, first appeared in 1928 for private circulation, obtaining the imprimatur of the Dublin diocese in 1937. Several further and expanded editions have been published and the Handbook has been translated into seventy-nine languages. His other publications include Can we be saints? (1922), The de Montfort way of true devotion to Mary (1947), The spirit of the Legion of Mary (1956), Edel Quinn (1960), Mary shall reign (1961), Miracles on tap (1961), Virgo Praedicanda (1967), True devotion to the nation (1971), The woman of Genesis (1976), and Victory through Mary (1981). In addition 33,000 letters from Duff to priests, legionaries, friends, and many others have been collected. Later in his life he received more formal recognition. In 1965 he was invited to attend the second Vatican council as a lay observer. On the occasion of his introduction there to the assembly by Archbishop Heenan of Liverpool, he was accorded a standing ovation; his ideas and organisation for involving the laity in the apostolate predated the council by forty years. He welcomed the council, but was perturbed in later life by the idea that Irish catholicism was being consumed by secularism through a failure to become apostolic. He was awarded the order of St Gregory the Great (1961) and an honorary doctorate of laws from the NUI (1968). In his last years he continued his enormous correspondence worldwide and gave many talks to legionaries and others. He continued to live in close proximity to the hostels that he had established, always taking a great interest in the residents. He died at home on 7 November 1980. With his death the wheel of Irish episcopal approval seemed to have turned full circle, Cardinal Tomas Ó Fiaich (qv) commenting that ‘perhaps the day may soon come when the church will declare him Irishman of the century’ (Irish Independent, 14 Nov. 1980). His cause for canonisation in the catholic church was introduced in the Dublin archdiocese in 1996.