Hennessey, Mary (1797–1875), Sister of Charity and pioneer in primary education, was born 8 February 1797 in Cork city, second daughter of George Hennessey, Cork wine merchant, and his wife Teresa Stacpoole, member of another Cork merchant family. Her father also served as captain of a yeomanry corps. While on military duty, he caught fever and died 13 April 1799, leaving Teresa with two small girls, Georgina and Mary. The girls were educated at the Ursuline Convent, Cork. When she grew up, Georgina married John Stuart Coxon, of Fleask Priory, Killarney. Mary, on leaving school, took her place in society, in Dublin and London as well as in Cork, enjoying a varied and pleasant social life. At the same time she was attracted to works of charity and loved to teach and help the poor, as had her cousin Mary Aikenhead (qv), who had founded the congregation of the Religious Sisters of Charity in 1815.
One winter, Mary was in Dublin, staying at the home of a friend, Mrs Anna Maria O'Brien, in Mountjoy Square. While there, she met a Jesuit priest who startled her by asking: ‘What are you going to do with yourself? To what purpose are you going to dedicate your life?’ This prompted her to turn her thoughts to the Sisters of Charity, founded by her cousin. She entered the noviciate in Stanhope St. on 13 February 1825, received the habit and the name ‘Sr Mary Xavier’ on 29 September 1825, and made her religious profession on 2 October 1827. Barely three years later, the work for which she became famous had begun.
The Sisters of Charity, founded for the service of the poor, had for their primary purpose the visitation of the sick poor, but they were also committed to instructing children and adults. In 1828, thanks to a legacy bequeathed to Archbishop Daniel Murray (qv) of Dublin by Archbishop Patrick Everard (qv) of Cashel for the building of schools for poor children, work was begun on the erection of a school in Upper Gardiner St., Dublin, to be run by the Sisters of Charity. S. M. Xavier was to be in charge. She and another sister began visiting all the ‘poor schools’ for girls in and around Dublin, in the hope that they might find a well organised system which they could adopt. Their efforts were not very successful, though they did pick up some useful hints. The school that came closest to what they were looking for was one on Meath St. run by a quaker, who kindly arranged that one of their teachers would come to Gardiner St. for six months to help establish the new foundation.
On 1 February 1830 the school was opened and the Meath St. system was given a fair trial. However, it proved unsatisfactory and the sisters found it impossible to establish order in the classrooms. At this point Providence intervened, sending help through the Christian Brothers, recently founded by Edmund Ignatius Rice (qv). S. M. Xavier appealed to Brother Rice for help and he responded by sending Brother Duggan, a young man who, besides being an excellent teacher, possessed control and organising power beyond the average. Not only did Brother Duggan establish order, but he also gave valuable training to the sisters and their assistants, showing them how to teach and how to win the respect and attention of their pupils.
S. M. Xavier, having overcome her initial difficulties with the help of Brother Duggan, gained such a reputation as an accomplished schoolmistress that bishops and other distinguished people often sought her advice on educational matters and on the organisation of ‘poor schools’ and provision of school meals. The Christian Brothers had a very valuable ‘School government book’ (privately circulated in MS copies), based largely on the Bell and Lancaster system, and S. M. Xavier, adapting this for use in girls' schools, compiled her own to be used in Gardiner St. and in any other establishments that the Sisters of Charity might have in the future. Members of other religious orders and congregations, including some from England, consulted her and came to see her methods in action. She remained active in the school up to her seventy-ninth year.
S. M. Xavier died 2 July 1875 and was laid to rest in the convent cemetery in Donnybrook, close to the grave of Mary Aikenhead.